Acids and Bases II | Chemistry

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This module explores how our body achieves this remarkable balancing act, and traces scientific discoveries that contributed to our current understanding of acid-base chemistry."> <meta name="keywords" content="science, education, STEM, math, biology, chemistry, physics, earth science, online learning"> <meta name="viewport" content="width=device-width, initial-scale=1.0, shrink-to-fit=no"> <meta name="msvalidate.01" content="D8E20F39AD48052260032E56DE409970"> <script type="application/ld+json"> { "@context": "http://schema.org/", "@type": "Article", "mainEntityOfPage": { "@type": "WebPage", "@id": "https://visionlearning.com/en/library/chemistry/1/acids-and-bases-ii/272" }, "name": "Acids and Bases II", "headline": "Acids and Bases II: Conjugate ions and buffers", "author": { "@type": "Person", "name": "Robin Marks, M.A." }, "datePublished": "2020-08-26 08:15:11", "dateModified": "2017-02-12T08:30:00+05:00", "image": { "@type": "ImageObject", "url": "/img/library/moduleImages/featured_image_272-23061209065128.jpg", "width": 696, "height": 464 }, "publisher": { "@type": "Organization", "name": "Visionlearning, Inc.", "logo": { "@type": "ImageObject", "url": "http://visionlearning.com/images/logo.png", "width": 278, "height": 60 } }, "description": "Our bodies constantly produce carbon dioxide, some of which stays in the blood and becomes carbonic acid. So what keeps blood from becoming too acidic? Our blood has a built-in buffering system that works to maintain a neutral pH. This module explores how our body achieves this remarkable balancing act, and traces scientific discoveries that contributed to our current understanding of acid-base chemistry.", "keywords": "science, education, STEM, math, biology, chemistry, physics, earth science, online learning", "inLanguage": { "@type": "Language", "name": "English", "alternateName": "en" }, "copyrightHolder": { "@type": "Organization", "name": "Visionlearning, Inc." }, "copyrightYear": "2020"} </script> <meta property="og:url" content="https://visionlearning.com/en/library/chemistry/1/acids-and-bases-ii/272"> <meta property="og:title" content="Acids and Bases II | Chemistry | Visionlearning" /> <meta property="og:type" content="website"> <meta property="og:site_name" content="Visionlearning"> <meta property="og:description" content="Our bodies constantly produce carbon dioxide, some of which stays in the blood and becomes carbonic acid. So what keeps blood from becoming too acidic? Our blood has a built-in buffering system that works to maintain a neutral pH. 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href="/en/library/environmental-science/61/biodiversity-i/276">Biodiversity I</a></li> <li><a href="/en/library/environmental-science/61/biodiversity-ii/281">Biodiversity II</a></li> <li><a href="/en/library/environmental-science/61/ecosystem-services/279">Ecosystem Services</a></li> <li><a href="/en/library/environmental-science/61/population-biology/287">Population Biology</a></li> </ul> </div> <button class="accordion__button" id="acc-button-earth-cycles" data-accordion="button" aria-controls="acc-panel-earth-cycles" aria-expanded="false"> <span class="accordion__button__label"> Earth Cycles </span> </button> <div class="accordion__panel" id="acc-panel-earth-cycles" data-accordion="panel" aria-labelledby="acc-button-earth-cycles" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/the-nitrogen-cycle/98">The Nitrogen Cycle</a></li> <li><a href="/en/library/environmental-science/61/the-carbon-cycle/95">The Carbon Cycle</a></li> <li><a href="/en/library/environmental-science/61/the-phosphorus-cycle/197">The Phosphorus Cycle</a></li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-research" data-accordion="button" aria-controls="acc-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/environmental-science/61/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-general-science" data-accordion="button" aria-controls="acc-panel-general-science" aria-expanded="false"> <span class="accordion__button__label"> General Science </span> </button> <div class="accordion__panel" id="acc-panel-general-science" data-accordion="panel" aria-labelledby="acc-button-general-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-methods" data-accordion="button" aria-controls="acc-panel-methods" aria-expanded="false"> <span class="accordion__button__label"> Methods </span> </button> <div class="accordion__panel" id="acc-panel-methods" data-accordion="panel" aria-labelledby="acc-button-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-scientific-method/45">The Scientific Method</a></li> </ul> </div> <button class="accordion__button" id="acc-button-measurement" data-accordion="button" aria-controls="acc-panel-measurement" aria-expanded="false"> <span class="accordion__button__label"> Measurement </span> </button> <div class="accordion__panel" id="acc-panel-measurement" data-accordion="panel" aria-labelledby="acc-button-measurement" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-metric-system/47">The Metric System</a></li> </ul> </div> <button class="accordion__button" id="acc-button-physical-properties" data-accordion="button" aria-controls="acc-panel-physical-properties" aria-expanded="false"> <span class="accordion__button__label"> Physical Properties </span> </button> <div class="accordion__panel" id="acc-panel-physical-properties" data-accordion="panel" aria-labelledby="acc-button-physical-properties" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/temperature/48">Temperature</a></li> <li><a href="/en/library/general-science/3/density-and-buoyancy/37">Density and Buoyancy</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-math-in-science" data-accordion="button" aria-controls="acc-panel-math-in-science" aria-expanded="false"> <span class="accordion__button__label"> Math in Science </span> </button> <div class="accordion__panel" id="acc-panel-math-in-science" data-accordion="panel" aria-labelledby="acc-button-math-in-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-equations" data-accordion="button" aria-controls="acc-panel-equations" aria-expanded="false"> <span class="accordion__button__label"> Equations </span> </button> <div class="accordion__panel" id="acc-panel-equations" data-accordion="panel" aria-labelledby="acc-button-equations" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/unit-conversion/144">Unit Conversion</a></li> <li><a href="/en/library/math-in-science/62/linear-equations/194">Linear Equations</a></li> <li><a href="/en/library/math-in-science/62/exponential-equations-i/206">Exponential Equations I</a></li> <li><a href="/en/library/math-in-science/62/exponential-equations-ii/210">Exponential Equations II</a></li> <li><a href="/en/library/math-in-science/62/scientific-notation/250">Scientific Notation</a></li> <li><a href="/en/library/math-in-science/62/measurement/257">Measurement</a></li> </ul> </div> <button class="accordion__button" id="acc-button-statistics" data-accordion="button" aria-controls="acc-panel-statistics" aria-expanded="false"> <span class="accordion__button__label"> Statistics </span> </button> <div class="accordion__panel" id="acc-panel-statistics" data-accordion="panel" aria-labelledby="acc-button-statistics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/introduction-to-descriptive-statistics/218">Introduction to Descriptive Statistics</a></li> <li><a href="/en/library/math-in-science/62/introduction-to-inferential-statistics/224">Introduction to Inferential Statistics</a></li> <li><a href="/en/library/math-in-science/62/statistical-techniques/239">Statistical Techniques</a></li> </ul> </div> <button class="accordion__button" id="acc-button-trigonometric-functions" data-accordion="button" aria-controls="acc-panel-trigonometric-functions" aria-expanded="false"> <span class="accordion__button__label"> Trigonometric Functions </span> </button> <div class="accordion__panel" id="acc-panel-trigonometric-functions" data-accordion="panel" aria-labelledby="acc-button-trigonometric-functions" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/wave-mathematics/131">Wave Mathematics</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-physics" data-accordion="button" aria-controls="acc-panel-physics" aria-expanded="false"> <span class="accordion__button__label"> Physics </span> </button> <div class="accordion__panel" id="acc-panel-physics" data-accordion="panel" aria-labelledby="acc-button-physics" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-light-and-optics" data-accordion="button" aria-controls="acc-panel-light-and-optics" aria-expanded="false"> <span class="accordion__button__label"> Light and Optics </span> </button> <div class="accordion__panel" id="acc-panel-light-and-optics" data-accordion="panel" aria-labelledby="acc-button-light-and-optics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/physics/24/the-nature-of-light/132">The Nature of Light</a></li> <li><a href="/en/library/physics/24/electromagnetism-and-light/138">Electromagnetism and Light</a></li> </ul> </div> <button class="accordion__button" id="acc-button-mechanics" data-accordion="button" aria-controls="acc-panel-mechanics" aria-expanded="false"> <span class="accordion__button__label"> Mechanics </span> </button> <div class="accordion__panel" id="acc-panel-mechanics" data-accordion="panel" aria-labelledby="acc-button-mechanics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/physics/24/defining-energy/199">Defining Energy</a></li> <li><a href="/en/library/physics/24/waves-and-wave-motion/102">Waves and Wave Motion</a></li> <li><a href="/en/library/physics/24/gravity/118">Gravity</a></li> <li><a href="/en/library/physics/24/thermodynamics-i/200">Thermodynamics I</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-process-of-science" data-accordion="button" aria-controls="acc-panel-process-of-science" aria-expanded="false"> <span class="accordion__button__label"> Process of Science </span> </button> <div class="accordion__panel" id="acc-panel-process-of-science" data-accordion="panel" aria-labelledby="acc-button-process-of-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-introduction" data-accordion="button" aria-controls="acc-panel-introduction" aria-expanded="false"> <span class="accordion__button__label"> Introduction </span> </button> <div class="accordion__panel" id="acc-panel-introduction" data-accordion="panel" aria-labelledby="acc-button-introduction" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-process-of-science/176">The Process of Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-the-culture-of-science" data-accordion="button" aria-controls="acc-panel-the-culture-of-science" aria-expanded="false"> <span class="accordion__button__label"> The Culture of Science </span> </button> <div class="accordion__panel" id="acc-panel-the-culture-of-science" data-accordion="panel" aria-labelledby="acc-button-the-culture-of-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-nature-of-scientific-knowledge/185">The Nature of Scientific Knowledge</a></li> <li><a href="/en/library/process-of-science/49/scientists-and-the-scientific-community/172">Scientists and the Scientific Community</a></li> <li><a href="/en/library/process-of-science/49/scientific-ethics/161">Scientific Ethics</a></li> <li><a href="/en/library/process-of-science/49/scientific-institutions-and-societies/162">Scientific Institutions and Societies</a></li> </ul> </div> <button class="accordion__button" id="acc-button-ideas-in-science" data-accordion="button" aria-controls="acc-panel-ideas-in-science" aria-expanded="false"> <span class="accordion__button__label"> Ideas in Science </span> </button> <div class="accordion__panel" id="acc-panel-ideas-in-science" data-accordion="panel" aria-labelledby="acc-button-ideas-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/theories-hypotheses-and-laws/177">Theories, Hypotheses, and Laws</a></li> <li><a href="/en/library/process-of-science/49/scientific-controversy/181">Scientific Controversy</a></li> <li><a href="/en/library/process-of-science/49/creativity-in-science/182">Creativity in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-research-methods" data-accordion="button" aria-controls="acc-panel-research-methods" aria-expanded="false"> <span class="accordion__button__label"> Research Methods </span> </button> <div class="accordion__panel" id="acc-panel-research-methods" data-accordion="panel" aria-labelledby="acc-button-research-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-practice-of-science/148">The Practice of Science</a></li> <li><a href="/en/library/process-of-science/49/experimentation-in-scientific-research/150">Experimentation in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/description-in-scientific-research/151">Description in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/comparison-in-scientific-research/152">Comparison in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/modeling-in-scientific-research/153">Modeling in Scientific Research</a></li> </ul> </div> <button class="accordion__button" id="acc-button-data" data-accordion="button" aria-controls="acc-panel-data" aria-expanded="false"> <span class="accordion__button__label"> Data </span> </button> <div class="accordion__panel" id="acc-panel-data" data-accordion="panel" aria-labelledby="acc-button-data" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/data-analysis-and-interpretation/154">Data Analysis and Interpretation</a></li> <li><a href="/en/library/process-of-science/49/uncertainty-error-and-confidence/157">Uncertainty, Error, and Confidence</a></li> <li><a href="/en/library/process-of-science/49/statistics-in-science/155">Statistics in Science</a></li> <li><a href="/en/library/process-of-science/49/using-graphs-and-visual-data-in-science/156">Using Graphs and Visual Data in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-communication" data-accordion="button" aria-controls="acc-panel-scientific-communication" aria-expanded="false"> <span class="accordion__button__label"> Scientific Communication </span> </button> <div class="accordion__panel" id="acc-panel-scientific-communication" data-accordion="panel" aria-labelledby="acc-button-scientific-communication" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/understanding-scientific-journals-and-articles/158">Understanding Scientific Journals and Articles</a></li> <li><a href="/en/library/process-of-science/49/utilizing-the-scientific-literature/173">Utilizing the Scientific Literature</a></li> <li><a href="/en/library/process-of-science/49/peer-review-in-scientific-publishing/159">Peer Review in Scientific Publishing</a></li> <li><a href="/en/library/process-of-science/49/the-how-and-why-of-scientific-meetings/186">The How and Why of Scientific Meetings</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-scientists-and-research" data-accordion="button" aria-controls="acc-panel-scientists-and-research" aria-expanded="false"> <span class="accordion__button__label"> Scientists and Research </span> </button> <div class="accordion__panel" id="acc-panel-scientists-and-research" data-accordion="panel" aria-labelledby="acc-button-scientists-and-research" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-scientific-research" data-accordion="button" aria-controls="acc-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/scientists-and-research/58/from-stable-chromosomes-to-jumping-genes/184">From Stable Chromosomes to Jumping Genes</a></li> <li><a href="/en/library/scientists-and-research/58/an-elegant-experiment-to-test-the-process-of-dna-replication/187">An Elegant Experiment to Test the Process of DNA Replication</a></li> <li><a href="/en/library/scientists-and-research/58/the-founding-of-neuroscience/233">The Founding of Neuroscience</a></li> <li><a href="/en/library/scientists-and-research/58/tracking-endangered-jaguars-across-the-border/189">Tracking Endangered Jaguars across the Border</a></li> <li><a href="/en/library/scientists-and-research/58/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> <li><a href="/en/library/scientists-and-research/58/revolutionizing-medicine-with-monoclonal-antibodies/220">Revolutionizing Medicine with Monoclonal Antibodies</a></li> <li><a href="/en/library/scientists-and-research/58/uncovering-the-mysteries-of-chronic-mountain-sickness/238">Uncovering the Mysteries of Chronic Mountain Sickness</a></li> </ul> </div> <button class="accordion__button" id="acc-button-profiles-in-science" data-accordion="button" aria-controls="acc-panel-profiles-in-science" aria-expanded="false"> <span class="accordion__button__label"> Profiles in Science </span> </button> <div class="accordion__panel" id="acc-panel-profiles-in-science" data-accordion="panel" aria-labelledby="acc-button-profiles-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/luis-e.-miramontes/232">Luis E. Miramontes</a></li> <li><a href="/en/library/scientists-and-research/58/bernardo-houssay/237">Bernardo Houssay</a></li> <li><a href="/en/library/scientists-and-research/58/craig-lee/256">Craig Lee</a></li> <li><a href="/en/library/scientists-and-research/58/david-ho/241">David Ho</a></li> <li><a href="/en/library/scientists-and-research/58/louis-tompkins-wright/244">Louis Tompkins Wright</a></li> <li><a href="/en/library/scientists-and-research/58/carlos-j.-finlay/217">Carlos J. Finlay</a></li> <li><a href="/en/library/scientists-and-research/58/cecilia-payne/290">Cecilia Payne</a></li> <li><a href="/en/library/scientists-and-research/58/jazmin-scarlett/291">Jazmin Scarlett</a></li> <li><a href="/en/library/scientists-and-research/58/ramari-stewart/292">Ramari Stewart</a></li> <li><a href="/en/library/scientists-and-research/58/johnson-cerda/300">Johnson Cerda</a></li> <li><a href="/en/library/scientists-and-research/58/ellen-ochoa/201">Ellen Ochoa</a></li> <li><a href="/en/library/scientists-and-research/58/ruth-benerito/205">Ruth Benerito</a></li> <li><a href="/en/library/scientists-and-research/58/franklin-chang-díaz/219">Franklin Chang Díaz</a></li> <li><a href="/en/library/scientists-and-research/58/percy-lavon-julian/221">Percy Lavon Julian</a></li> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229">Luis Walter Alvarez</a></li> <li><a href="/en/library/scientists-and-research/58/france-anne-dominic-córdova/230">France Anne-Dominic Córdova</a></li> </ul> </div> </div> </div> </div> </div> </li> <li>  <button class="button" data-toggle="dropdown">Chemistry </button> <div class="nav__dropdown box-shadow-1 padding-1"> <div class="accordion accordion--secondary font-size-sm"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-sub-button-atomic-theory-and-structure" data-accordion="button" aria-controls="acc-sub-panel-atomic-theory-and-structure" aria-expanded="false"> <span class="accordion__button__label"> Atomic Theory and Structure </span> </button> <div class="accordion__panel" id="acc-sub-panel-atomic-theory-and-structure" data-accordion="panel" aria-labelledby="acc-sub-button-atomic-theory-and-structure" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/chemistry/1/early-ideas-about-matter/49">Early Ideas about Matter</a></li> <li><a href="/en/library/chemistry/1/the-periodic-table-of-elements-i/52">The Periodic Table of Elements I</a></li> <li><a href="/en/library/chemistry/1/the-periodic-table-of-elements-ii/296">The Periodic Table of Elements II</a></li> <li><a href="/en/library/chemistry/1/the-periodic-table-of-elements-iii/297">The Periodic Table of Elements III</a></li> <li><a href="/en/library/chemistry/1/the-periodic-table-of-elements-iv/298">The Periodic Table of Elements IV</a></li> <li><a href="/en/library/chemistry/1/the-periodic-table-of-elements-v/299">The Periodic Table of Elements V</a></li> <li><a href="/en/library/chemistry/1/atomic-theory-i/50">Atomic Theory I</a></li> <li><a href="/en/library/chemistry/1/atomic-theory-ii/51">Atomic Theory II</a></li> <li><a href="/en/library/chemistry/1/atomic-theory-iii/223">Atomic Theory III</a></li> <li><a href="/en/library/chemistry/1/atomic-theory-iv/231">Atomic Theory IV</a></li> <li><a href="/en/library/chemistry/1/the-mole-and-atomic-mass/53">The Mole and Atomic Mass</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-physical-states-and-properties" data-accordion="button" aria-controls="acc-sub-panel-physical-states-and-properties" aria-expanded="false"> <span class="accordion__button__label"> Physical States and Properties </span> </button> <div class="accordion__panel" id="acc-sub-panel-physical-states-and-properties" data-accordion="panel" aria-labelledby="acc-sub-button-physical-states-and-properties" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/chemistry/1/states-of-matter/120">States of Matter</a></li> <li><a href="/en/library/chemistry/1/substances/280">Substances</a></li> <li><a href="/en/library/chemistry/1/properties-of-solids/209">Properties of Solids</a></li> <li><a href="/en/library/chemistry/1/properties-of-liquids/222">Properties of Liquids</a></li> <li><a href="/en/library/chemistry/1/properties-of-gases/245">Properties of Gases</a></li> <li><a href="/en/library/chemistry/1/diffusion-i/216">Diffusion I</a></li> <li><a href="/en/library/chemistry/1/kinetic-molecular-theory/251">Kinetic-Molecular Theory</a></li> <li><a href="/en/library/chemistry/1/solutions/266">Solutions</a></li> <li><a href="/en/library/chemistry/1/water/267">Water</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-chemical-relationships" data-accordion="button" aria-controls="acc-sub-panel-chemical-relationships" aria-expanded="false"> <span class="accordion__button__label"> Chemical Relationships </span> </button> <div class="accordion__panel" id="acc-sub-panel-chemical-relationships" data-accordion="panel" aria-labelledby="acc-sub-button-chemical-relationships" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/chemistry/1/chemical-bonding/55">Chemical Bonding</a></li> <li><a href="/en/library/chemistry/1/stoichiometry/270">Stoichiometry</a></li> <li><a href="/en/library/chemistry/1/chemical-equations/268">Chemical Equations</a></li> <li><a href="/en/library/chemistry/1/acids-and-bases-i/271">Acids and Bases I</a></li> <li class="current">Acids and Bases II</li> </ul> </div> <button class="accordion__button" id="acc-sub-button-reactions-and-changes" data-accordion="button" aria-controls="acc-sub-panel-reactions-and-changes" aria-expanded="false"> <span class="accordion__button__label"> Reactions and Changes </span> </button> <div class="accordion__panel" id="acc-sub-panel-reactions-and-changes" data-accordion="panel" aria-labelledby="acc-sub-button-reactions-and-changes" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/chemistry/1/chemical-reactions/54">Chemical Reactions</a></li> <li><a href="/en/library/chemistry/1/chemical-reactions-ii/278">Chemical Reactions II</a></li> <li><a href="/en/library/chemistry/1/nuclear-chemistry-i/284">Nuclear Chemistry I</a></li> <li><a href="/en/library/chemistry/1/carbon-chemistry/60">Carbon Chemistry</a></li> </ul> </div> </div> </div> </div> </li> </ul> </nav>  <div id="theTop"></div> <main id="skip-header-content"> <div class="margin-bottom-5"> <article class="container wide module"> <header class="grid grid--sidebar-right module__header"> <div class="module__header__title"> <span class="subcategory"> <strong><em>Chemical Relationships</em></strong> </span> <h1>Acids and Bases II: <sub><em>Conjugate ions and buffers</em></sub></h1> <p class="byline">by Robin Marks, M.A.</p> <nav class="module__header__tabs"> <ul class="tabs-nav tabs-nav--horizontal library"> <li> <a href="/en/library/chemistry/1/acids-and-bases-ii/272/reading" aria-current="page" >Reading</a> </li> <li> <a href="/en/library/chemistry/1/acids-and-bases-ii/272/quiz">Quiz</a> </li> <li> <a href="/en/library/chemistry/1/acids-and-bases-ii/272/resources">Teach with this</a> </li> </ul> </nav> </div> </header> <hr class="divider"/>   <div class="grid grid--sidebar-right grid--divider"> <div class="order-2 order-1--lg module__main"> <div class="narrow margin-x-auto margin-y-5"> <div class="accordion margin-bottom-5">  <button class="accordion__button" id="acc-button-key-concepts" data-accordion="button" aria-controls="acc-panel-key-concepts" aria-expanded="true" tabindex="0"> Did you know? </button> <div class="accordion__panel shown show" id="acc-panel-key-concepts" data-accordion="panel" aria-labelledby="acc-button-key-concepts" role="region"> <div class="accordion__panel__content"> <p>We think of water as neutral, but did you know that water can act as both an acid and a base? This is one of water’s most important roles in our body chemistry. Key to the body’s pH-control system is this property of water that allows it to donate or accept protons to keep our body fluids and tissues in a state of equilibrium. Acid-base chemistry is also important to many other common processes such as dying fabrics, producing everyday grooming products, and manufacturing life-saving medications.</p> </div> </div>  <button class="accordion__button" id="acc-button-table-of-contents" data-accordion="button" aria-controls="acc-panel-table-of-contents" aria-expanded="false" tabindex="0"> Key concepts </button> <div class="accordion__panel" id="acc-panel-table-of-contents" data-accordion="panel" aria-labelledby="acc-button-table-of-contents" role="region" aria-hidden="true"> <div class="accordion__panel__content"> <ul class="bulleted"> <li><p>The Brønsted-Lowry system defines a conjugate base as an acid without its proton, and a conjugate acid as a base with an additional proton.</p></li> <li><p>Water is amphoteric, meaning it can act as both an acid and a base, accepting a proton to become a hydronium ion (H<sub>3</sub>O+), or dissociating into a proton and a hydroxide ion (OH-).</p></li> <li><p>The strength of an acid is based on its tendency to ionize in water, not on the concentration of the acid in a solution </p></li> <li><p>Buffers are solutions containing a weak acid and its conjugate base, allowing them to absorb a strong acid or base without much change in pH.</p></li></ul> </div> </div>  <button class="accordion__button" id="acc-button-terms-you-should-know" data-accordion="button" aria-controls="acc-panel-terms-you-should-know" aria-expanded="false" tabindex="0"> Terms you should know </button> <div class="accordion__panel" id="acc-panel-terms-you-should-know" data-accordion="panel" aria-labelledby="acc-button-terms-you-should-know" role="region" aria-hidden="true"> <div class="accordion__panel__content"> <dl> <dt>acidosis </dt> <dd> a condition in which your body’s pH is out of balance and the blood and body tissues are too acidic. </dd> <dt><a href="/en/glossary/view/hydronium+ion">hydronium ion </a></dt> <dd> also called hydronium, this is the positively charged molecule that results in an acidic solution when water (H2O) acts like a base and accepts a proton (H+), becoming H3O+.</dd> </dl> </div> </div> </div> <hr class="border-color-dark" /> <section> <div class="container narrow"> <p>Ah, pizza—and the indigestion it can cause. In our <a href="/library/module_viewer.php?mid=271">Acids and <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">Bases</mark> I: Definitions, <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark> and neutralization</a>I module, we looked how antacids can act as a base to neutralize pizza’s acidic tomato sauce and cheese. Antacids contain calcium carbonate, which <mark class="term" data-term="dissociate" data-term-def="The breaking apart of a molecule, especially in the presence of heat or a polar solvent. For example, the ionic&hellip;" data-term-url="/en/glossary/view/dissociate/1561">dissociates</mark> and releases a carbonate <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ion</mark> (CO<sub>3</sub><suo>-</sup>). The carbonate mops up H+ <mark class="term" data-term="ion" data-term-url="/en/glossary/view/ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;">ions</mark>, reducing the acidity in your stomach, according to the equation: </p> <div class="figure"><figure> $$2H^+(aq) + CO_{3-} \rightarrow H2_3CO_3$$ <figcaption><strong>Equation 1</strong></figcaption> </figure></div><div class="figure"><figure> <a href="https://visionlearning.com/images/figure-images/272-a-2x.png" title="Pizza"> <span class="fa fa-search-plus"></span> <img src="https://visionlearning.com/images/figure-images/272-a.png" alt="Pizza"> </a> <figcaption> <strong>Figure 1</strong>: Pizza </figcaption> </figure></div><p>But even if you don’t take an antacid, your body manages to adjust your digestive <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">system</mark> to the proper <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark>. And your body is constantly producing carbon dioxide, some of which you breathe out, but some of which stays in your blood and combines with water to create carbonic <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark>. So how does your body maintain a pH that keeps it functioning, regardless of what you’re exposed to?</p> <p>Physiologists and chemists became very interested in this question of internal acid/base balance in the late 1800s, driven by a desire to treat people for whom that balancing mechanism wasn’t working, a condition called acidosis (a condition in which acid builds up in the blood). These scientists’ efforts to better understand how the body achieves its pH balance resulted in a much richer picture of what actually happens between acids and <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">bases</mark> in <mark class="term" data-term="solution" data-term-def="A mixture of more than one substance with properties that do not vary within the sample. Commonly used to describe a&hellip;" data-term-url="/en/glossary/view/solution/1571">solution</mark>. This knowledge continues to play an important role in treating acidosis, which is common among people with kidney disease or diabetes.</p> <p><section id="toc_1" class=""> <h2>Equilibrium: A Balancing Act</h2></p> <div class="figure"><figure><a title="Lawrence Henderson" href="https://visionlearning.com/images/figure-images/272-b-2x.jpg"> <img src="https://visionlearning.com/images/figure-images/272-b.jpg" alt="Lawrence Henderson"> </a> <figcaption><strong>Figure 2</strong>: Lawrence Henderson’s interest in biochemistry led him to study the dissociation reactions of bicarbonate. He determined that the ions involved in the acid’s equilibrium are central to how the body maintains its steady internal pH. His biochemical investigations would result in major contributions to acid-base chemistry, including the Henderon-Hasselbalch equation, which is used to calculate pH of a solution.</figcaption> </figure></div><p>In the early 20th century chemists began to clearly understand how <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ions</mark>, including those of <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acids</mark> and <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">bases</mark>, behave in water. A promising young Harvard biochemist named Lawrence Henderson applied this new understanding to biological <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">systems</mark>. He knew that patients with acidosis improved when they got an injection of bicarbonate, which occurs naturally in the body. Henderson studied the <mark class="term" data-term="equilibrium" data-term-def="A state of balance between opposing forces; a state of balance in which opposing forces cancel one another. A state in&hellip;" data-term-url="/en/glossary/view/equilibrium/8680">equilibrium</mark> and dissociation <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reactions</mark> of bicarbonate, and, in a landmark paper, he described his conclusion that these <mark class="term" data-term="ion" data-term-url="/en/glossary/view/ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;">ions</mark> and other <mark class="term" data-term="Weak acid" data-term-def="An acid that partially dissociates into its constituent ions in water." data-term-url="/en/glossary/view/Weak+acid/12079">weak acids</mark> made up the body’s pH-control system. </p><p>What went into Hendersonâs reasoning? He knew that carbonic acid dissociates in water, releasing a proton:<div class="figure"><figure> $$H_3CO_3 \rightarrow H^+ + HCO_{3^-}$$ <figcaption><strong>Equation 2</strong></figcaption> </figure></div></p><p>Research at the time was revealing that this equation is only partially correct, because it leaves water out of the picture. But water actually plays an important role in acid-base chemistry. In an acidic solution, water acts like a Bronsted-Lowry base by accepting a proton released by the acid (See our <a href="/library/module_viewer.php?mid=271">Acids and Bases I: Definitions, pH and Neutralization</a> module to review this definition of acids and bases):<div class="figure"><figure> $$H^+ + H_2O \rightarrow H_3O^+$$ <figcaption><strong>Equation 3</strong></figcaption> </figure></div></p><p>The resulting positively charged molecule is called a hydronium ion (H<sub>3</sub>O<sup>+</sup>). In fact, this reaction to form hydronium ions even occurs in a glass of pure water. Because water is polar, and is constantly engaging in hydrogen bonding with other water molecules, a very small number of those molecules dissociate into their constituent ions as in equation 4 below:<div class="figure"><figure> $$2H_2O \leftrightarrow H_3O^+ + OH^-$$ <figcaption><strong>Equation 4</strong></figcaption> </figure></div></p><p>The two-sided arrow shows that the <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reaction</mark> happens in both the forward direction (left to right) and the reverse direction (right to left) at the same time. In other words, while some water <mark class="term" data-term="molecule" data-term-def="A particle formed by the chemical bonding of two or more atoms. The molecule is the smallest particle of a&hellip;" data-term-url="/en/glossary/view/molecule/1518">molecules</mark> are taking on a hydrogen <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ion</mark> to become hydronium and forming hydroxide (OH<sup>-</sup>), some <mark class="term" data-term="Hydronium ion" data-term-def="A positively charged water molecule that has taken on an additional proton, to be H-3O+." data-term-url="/en/glossary/view/Hydronium+ion/12076">hydronium ions</mark> are losing a hydrogen ion to become water. When the forward reaction is happening at the same rate as the reverse reaction, a condition we call <mark class="term" data-term="equilibrium" data-term-def="A state of balance between opposing forces; a state of balance in which opposing forces cancel one another. A state in&hellip;" data-term-url="/en/glossary/view/equilibrium/8680">equilibrium</mark>, the <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark> of water is 7.0, which is what we consider <mark class="term" data-term="neutral" data-term-def="Generally defined as neither one thing nor another. 1. Electrically neutral refers to having no net electrical charge, usually achieved&hellip;" data-term-url="/en/glossary/view/neutral/855">neutral</mark>.</p><p>However, this <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reaction</mark> can be influenced by other components in the water – add a <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark> to water and some of the <mark class="term" data-term="Hydronium ion" data-term-def="A positively charged water molecule that has taken on an additional proton, to be H-3O+." data-term-url="/en/glossary/view/Hydronium+ion/12076">hydronium ions</mark> react without to form water. Add an <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> to water, and you shift the <mark class="term" data-term="equilibrium" data-term-def="A state of balance between opposing forces; a state of balance in which opposing forces cancel one another. A state in&hellip;" data-term-url="/en/glossary/view/equilibrium/8680">equilibrium</mark> towards formation of more hydronium <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ions</mark>. Water is, in fact, one of several <mark class="term" data-term="molecule" data-term-def="A particle formed by the chemical bonding of two or more atoms. The molecule is the smallest particle of a&hellip;" data-term-url="/en/glossary/view/molecule/1518">molecules</mark> with the capacity to act both as an acid and as a base. Such molecules are called <mark class="term" data-term="Amphoteric" data-term-def="Describing a molecule that can act as both an acid and a base." data-term-url="/en/glossary/view/Amphoteric/12073">amphoteric</mark>. </p><p>Adding the role that water plays into Equation 2, we get a more complete picture of whatâs happening in the carbonic acid solution:<div class="figure"><figure> $$H_2CO_3 + H_2O \leftrightarrow H_3O^+ + {HCO_3}^-$$ <figcaption><strong>Equation 5</strong></figcaption> </figure></div></p><p>Thus, water isn’t simply a bystander, but rather participates in the <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reaction</mark>. The addition of <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> to the <mark class="term" data-term="solution" data-term-def="A mixture of more than one substance with properties that do not vary within the sample. Commonly used to describe a&hellip;" data-term-url="/en/glossary/view/solution/1571">solution</mark> shifts the <mark class="term" data-term="equilibrium" data-term-def="A state of balance between opposing forces; a state of balance in which opposing forces cancel one another. A state in&hellip;" data-term-url="/en/glossary/view/equilibrium/8680">equilibrium</mark> towards the creation of <mark class="term" data-term="Hydronium ion" data-term-def="A positively charged water molecule that has taken on an additional proton, to be H-3O+." data-term-url="/en/glossary/view/Hydronium+ion/12076">hydronium ions</mark> (H<sub>3</sub>O<sup>+</sup>), making the solution acidic. This is true for all acid-base reactions.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc12239"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">Water can act as both an acid and a base.</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-12239-0-option-a" name="quiz-option-12239" type="radio" value="True" > <span class="option__label"> <span class="screen-reader-only">a.</span> True </span> </label> <span class="quiz__response" id="response-12239-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-12239-1-option-b" name="quiz-option-12239" type="radio" value="False" > <span class="option__label"> <span class="screen-reader-only">b.</span> False </span> </label> <span class="quiz__response" id="response-12239-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_2"> <h2>Conjugate <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">Acids</mark>, <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">Bases</mark> & <mark class="term" data-term="Amphoteric" data-term-def="Describing a molecule that can act as both an acid and a base." data-term-url="/en/glossary/view/Amphoteric/12073">Amphoteric</mark> Molecules</h2><p>Let’s look a little more closely at how this plays out with our carbonic <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> example. Equation 5 shows that water has accepted a dissociated <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">proton</mark> from the <mark class="term" data-term="carbonic acid" data-term-def="The weak acid formed when CO<sub>2</sub> dissolves in water." data-term-url="/en/glossary/view/carbonic+acid/2192">carbonic acid</mark>. As we saw, in water, carbonic acid <mark class="term" data-term="dissociate" data-term-def="The breaking apart of a molecule, especially in the presence of heat or a polar solvent. For example, the ionic&hellip;" data-term-url="/en/glossary/view/dissociate/1561">dissociates</mark> according to the equation:</p><div class="figure"><figure> <a href="https://visionlearning.com/images/figure-images/272-c-2xpng" title="Carbonic Acid"> <span class="fa fa-search-plus"></span> <img src="https://visionlearning.com/images/figure-images/272-c.png" alt="Carbonic Acid Table"> </a> <figcaption> <strong>Table 1</strong>: Equation 5 </figcaption> </figure></div><p>In this <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reaction</mark> (Eqn. 5), carbonic <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> donates a <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">proton</mark> and water acts as a <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark> by accepting the proton. The resulting <mark class="term" data-term="product" data-term-def="The material that is formed as a result of a chemical reaction. Written on the right side of a chemical equation.&hellip;" data-term-url="/en/glossary/view/product/1569">products</mark> are a bicarbonate <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ion</mark> that formed when <mark class="term" data-term="carbonic acid" data-term-def="The weak acid formed when CO<sub>2</sub> dissolves in water." data-term-url="/en/glossary/view/carbonic+acid/2192">carbonic acid</mark> lost its proton and the <mark class="term" data-term="Hydronium ion" data-term-def="A positively charged water molecule that has taken on an additional proton, to be H-3O+." data-term-url="/en/glossary/view/Hydronium+ion/12076">hydronium ion</mark> that formed when water accepted it. The hydronium ion is called the <mark class="term" data-term="Conjugate acid" data-term-def="Conjugate acid: In an acid-base reaction, the conjugate acid is the species that results when the original base accepts a proton&hellip;" data-term-url="/en/glossary/view/Conjugate+acid/12074">conjugate acid</mark> of water. A conjugate acid of a reaction is the <mark class="term" data-term="species" data-term-def="1. In biological classifications, it is the lowest and most basic unit of the Linnaean taxonomic hierarchy (although it is also&hellip;" data-term-url="/en/glossary/view/species/893">species</mark> that has accepted the proton from the <mark class="term" data-term="reactant" data-term-def="The initial material that participates in a chemical reaction. Written on the left side of a chemical equation. Compare&hellip;" data-term-url="/en/glossary/view/reactant/1568">reactant</mark> that donated it. In this case, the hydronium ion is able to react as an acid in another reaction, donating the proton it gained. The bicarbonate ion is the <mark class="term" data-term="Conjugate base" data-term-def="In an acid-base reaction, the conjugate base is the species that results when the original acid donates a proton to the&hellip;" data-term-url="/en/glossary/view/Conjugate+base/12075">conjugate base</mark>, the species that lost a proton in the initial reaction, A conjugate base is able to accept a proton in another <mark class="term" data-term="chemical reaction" data-term-def="A process in which atoms and molecules recombine by forming or breaking chemical bonds. Chemical reactions form new products that&hellip;" data-term-url="/en/glossary/view/chemical+reaction/1547">chemical reaction</mark>.</p><p>This phenomenon always happens in pairs. The <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> in a <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reaction</mark> always produces a conjugate <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark> when it gives up its <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">proton</mark>, and the original base always produces the <mark class="term" data-term="Conjugate acid" data-term-def="Conjugate acid: In an acid-base reaction, the conjugate acid is the species that results when the original base accepts a proton&hellip;" data-term-url="/en/glossary/view/Conjugate+acid/12074">conjugate acid</mark> when it accepts the proton. The four pieces always exist together, whether it is water acting on the original acid or another <mark class="term" data-term="compound" data-term-def="A material formed by the chemical combination of elements in defined proportions. Compounds can be chemically decomposed into simpler substances." data-term-url="/en/glossary/view/compound/1517">compound</mark>. </p><p>The two-sided arrow in Eqn. 5 tells us that the <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reaction</mark> is happening in both the forward and reverse directions. In a <mark class="term" data-term="solution" data-term-def="A mixture of more than one substance with properties that do not vary within the sample. Commonly used to describe a&hellip;" data-term-url="/en/glossary/view/solution/1571">solution</mark> of carbonic <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> and water, acid and <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark> <mark class="term" data-term="molecule" data-term-def="A particle formed by the chemical bonding of two or more atoms. The molecule is the smallest particle of a&hellip;" data-term-url="/en/glossary/view/molecule/1518">molecules</mark> are constantly reacting to form <mark class="term" data-term="Conjugate base" data-term-def="In an acid-base reaction, the conjugate base is the species that results when the original acid donates a proton to the&hellip;" data-term-url="/en/glossary/view/Conjugate+base/12075">conjugate base</mark> and <mark class="term" data-term="Conjugate acid" data-term-def="Conjugate acid: In an acid-base reaction, the conjugate acid is the species that results when the original base accepts a proton&hellip;" data-term-url="/en/glossary/view/Conjugate+acid/12074">conjugate acid</mark> molecules, and at the same time, the conjugate acid and base molecules are reacting to form the original acid and base </p><p>A similar phenomenon happens when a <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark> is mixed with water. Remember that water is <mark class="term" data-term="Amphoteric" data-term-def="Describing a molecule that can act as both an acid and a base." data-term-url="/en/glossary/view/Amphoteric/12073">amphoteric</mark>, able to act as both an <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> and a base, depending on the conditions. Let’s look at what happens when we put a base, in this case ammonia (NH<sub>3</sub>), in water:</p><div class="figure"><figure> <a href="https://visionlearning.com/images/figure-images/272-d-2x.png" title="Ammonia Table"> <span class="fa fa-search-plus"></span> <img src="https://visionlearning.com/images/figure-images/272-d.png" alt="Ammonia Table"> </a> <figcaption> <strong>Table 2</strong>: Equation 6 </figcaption> </figure></div><p>In the forward direction of this <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reaction</mark>, water is donating a <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">proton</mark> to NH<sub>3</sub>. In the reverse direction, the OH<sup>-</sup> <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ion</mark> acts as the conjugate <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark>, because it can accept a proton donated by the conjugate <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark>, NH<sub>4</sub><sup>+</sup>.</p><p>Equation 3 and Equation 4 demonstrate how water is <mark class="term" data-term="Amphoteric" data-term-def="Describing a molecule that can act as both an acid and a base." data-term-url="/en/glossary/view/Amphoteric/12073">amphoteric</mark>. It turns out that the bicarbonate <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ion</mark> Lawrence Henderson wrote about in the early 1900s is also amphoteric and can act as either an <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> or a <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark>. In other words, bicarbonate can accept a <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">proton</mark>, as the <mark class="term" data-term="Conjugate base" data-term-def="In an acid-base reaction, the conjugate base is the species that results when the original acid donates a proton to the&hellip;" data-term-url="/en/glossary/view/Conjugate+base/12075">conjugate base</mark> does in the reverse <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reaction</mark> in Equation 5, or it can donate a proton, to become a carbonate ion (creating a <mark class="term" data-term="Hydronium ion" data-term-def="A positively charged water molecule that has taken on an additional proton, to be H-3O+." data-term-url="/en/glossary/view/Hydronium+ion/12076">hydronium ion</mark> in the process).</p><div class="figure"><figure> <a href="https://visionlearning.com/images/figure-images/272-e-2x.png" title="Carbonic Acid Equilibrium"> <span class="fa fa-search-plus"></span> <img src="https://visionlearning.com/images/figure-images/272-e.png" alt="Carbonic Acid Equilibrium"> </a> <figcaption> <strong>Figure 5</strong>: Carbonic Acid Equilibrium </figcaption> </figure></div><p>While Henderson had uncovered a central clue in the story of how the body maintains its <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark> balance, he wasn’t able to explain exactly how that happens until he read the <mark class="term" data-term="work" data-term-def="A process that occurs when a force acts over a distance, as when an object is moved. Work equals the multiple&hellip;" data-term-url="/en/glossary/view/work/1502">work</mark> of another chemist.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc12248"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">The acid in a conjugate acid-base reaction always produces a conjugate base when it __________ a proton.</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-12248-0-option-a" name="quiz-option-12248" type="radio" value="gives up" > <span class="option__label"> <span class="screen-reader-only">a.</span> gives up </span> </label> <span class="quiz__response" id="response-12248-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-12248-1-option-b" name="quiz-option-12248" type="radio" value="accepts" > <span class="option__label"> <span class="screen-reader-only">b.</span> accepts </span> </label> <span class="quiz__response" id="response-12248-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_3"> <h2>Strong versus weak acids</h3><p>Before getting further into our explanation of how bicarbonate <mark class="term" data-term="control" data-term-def="In science, a control is a system for which the expected change or outcome is well known and is measured or&hellip;" data-term-url="/en/glossary/view/control/3801">controls</mark> blood <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark>, we need to define some differences between strong and weak <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acids</mark>. Hydrochloric acid, HCl, is a <mark class="term" data-term="Strong acid" data-term-def="An acid that completely dissociates into its constituent ions in water." data-term-url="/en/glossary/view/Strong+acid/12077">strong acid</mark> that’s found in your stomach, where it helps break down food. It can also break down fabric or skin, leaving burn holes in both. <mark class="term" data-term="carbonic acid" data-term-def="The weak acid formed when CO<sub>2</sub> dissolves in water." data-term-url="/en/glossary/view/carbonic+acid/2192">Carbonic acid</mark>, on the other hand, is a <mark class="term" data-term="Weak acid" data-term-def="An acid that partially dissociates into its constituent ions in water." data-term-url="/en/glossary/view/Weak+acid/12079">weak acid</mark>. Not only can you spill it all over your clothes and skin without consequence, you can pump it through your entire body.</p><p>So, what makes one acid strong and another weak? It is not the amount of acid that is used but rather the amount of acid that actually ionizesâdissociates into its constituent ionsâin water.<p>When you add hydrochloric acid to water:</p><div class="figure"><figure> $$HCl \rightarrow H^+ + Cl^-$$ <figcaption><strong>Equation 8</strong></figcaption> </figure></div></p><p>All of the HCl molecules dissociate, leaving only H+ and Cl- ions, and there are no molecules of HCl remaining. This reaction only goes in the forward reaction (thus the single-headed arrow in the equation); the resulting products remain dissociated. Acids that completely dissociate in water are referred to as strong acids.<p>Dissolving carbonic acid in water, however, is different:</p><div class="figure"><figure> $$H_2CO_3 + H_2O \leftrightarrow H_3O^+ + {HCO_3}^-$$ <figcaption><strong>Equation 5</strong></figcaption> </figure></div></p><p>While some of the carbonic acid dissociates into ions, some of those resulting ions will join together to form carbonic acid again. Thus, at any given time, there will be both carbonic acid molecules and bicarbonate ions in the solution. This is the definition of a weak acid, one that does not dissociate completely in water. In solutions containing weak acids, both the forward and reverse reactions are always happening at the same time, and we indicate this by using the two-sided arrow in the equation.<p>These definitions of strong vs. weak apply to bases as well. NaOH (sodium hydroxide), a strong base, completely dissociates in water:</p><div class="figure"><figure> $$NaOH \rightarrow Ha^+ + OH^-$$ <figcaption><strong>Equation 9</strong></figcaption> </figure></div></p><p>This leaves only ions, and no NaOH molecules in the solution. Ammonia (NH3), on the other hand, is a weak base:<div class="figure"><figure> $$NH_3 + H_2O \leftrightarrow OH^- \text{ and } {NH_4}^-$$ <figcaption><strong>Equation 6</strong></figcaption> </figure></div></p><p>At any given moment, some ammonia <mark class="term" data-term="molecule" data-term-def="A particle formed by the chemical bonding of two or more atoms. The molecule is the smallest particle of a&hellip;" data-term-url="/en/glossary/view/molecule/1518">molecules</mark> will remain uncharged while others take on a <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">proton</mark> from water to become <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ions</mark>. </p></section> <section id="toc_4"> <h2>Weak <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acids</mark> and their conjugate <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">bases</mark> make good buffers</h2><p>At about the same time that Henderson was studying the bicarbonate <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">system</mark>, the Danish chemist Sören Sörenson was investigating a concept that would explain how bicarbonate <mark class="term" data-term="work" data-term-def="A process that occurs when a force acts over a distance, as when an object is moved. Work equals the multiple&hellip;" data-term-url="/en/glossary/view/work/1502">works</mark> its magic. Sörenson was interested in biological <mark class="term" data-term="molecule" data-term-def="A particle formed by the chemical bonding of two or more atoms. The molecule is the smallest particle of a&hellip;" data-term-url="/en/glossary/view/molecule/1518">molecules</mark> called <mark class="term" data-term="enzyme" data-term-def="Molecules produced by living organisms that help catalyze biochemical reactions. Enzymes are predominantly protein or protein-based molecules and are highly&hellip;" data-term-url="/en/glossary/view/enzyme/1595">enzymes</mark>, <mark class="term" data-term="protein" data-term-def="Macromolecules that are polymers of individual amino acids arranged in a chain and joined together by peptide bonds (and so also&hellip;" data-term-url="/en/glossary/view/protein/1594">protein</mark> molecules that catalyze <mark class="term" data-term="chemical reaction" data-term-def="A process in which atoms and molecules recombine by forming or breaking chemical bonds. Chemical reactions form new products that&hellip;" data-term-url="/en/glossary/view/chemical+reaction/1547">chemical reactions</mark> in living things. Sörenson noticed that enzymes work best within a very small <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark> range. His study of how proteins maintain this range led to the paper in which he proposed his now-famous pH <mark class="term" data-term="scale" data-term-def="An instrument for measuring heat energy or weight in which units are marked at intervals; a system for quantifying heat energy&hellip;" data-term-url="/en/glossary/view/scale/8536">scale</mark>. </p><p>That paper was published just a few months after Henderson’s study of bicarbonates. Along with describing the <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark> <mark class="term" data-term="scale" data-term-def="An instrument for measuring heat energy or weight in which units are marked at intervals; a system for quantifying heat energy&hellip;" data-term-url="/en/glossary/view/scale/8536">scale</mark>, Sörenson’s paper explained some <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> he had done to discern how the body maintains the narrow pH range an <mark class="term" data-term="enzyme" data-term-def="Molecules produced by living organisms that help catalyze biochemical reactions. Enzymes are predominantly protein or protein-based molecules and are highly&hellip;" data-term-url="/en/glossary/view/enzyme/1595">enzyme</mark> requires. If he added a weak <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> to water, the pH would go down. No surprise there. But, Sörenson discovered, if he added that same <mark class="term" data-term="Weak acid" data-term-def="An acid that partially dissociates into its constituent ions in water." data-term-url="/en/glossary/view/Weak+acid/12079">weak acid</mark> and its sodium <mark class="term" data-term="salt" data-term-def="Generally, any ionic compound except those that contain hydroxide or hydrogen ions. Specifically, any compound other than water formed by&hellip;" data-term-url="/en/glossary/view/salt/1575">salt</mark> (the weak acid combined with a sodium ion), the pH barely budged. In this way, he effectively added more conjugate <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark> to the <mark class="term" data-term="solution" data-term-def="A mixture of more than one substance with properties that do not vary within the sample. Commonly used to describe a&hellip;" data-term-url="/en/glossary/view/solution/1571">solution</mark>, and found that it stabilized the hydrogen <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ion</mark> <mark class="term" data-term="concentration" data-term-def="The amount of one substance in relation to other components within a given area." data-term-url="/en/glossary/view/concentration/8733">concentration</mark>. We can explain why by looking at the <mark class="term" data-term="ion" data-term-url="/en/glossary/view/ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;">ions</mark> involved. </p><p>We already know that carbonic acid dissociates according to this equation (Eqn. 5):<div class="figure"><figure> $$H_2CO_3 + H_2O \leftrightarrow H_3O^+ + HCO_3$$ </figure></div><p>Sodium bicarbonate (which is the chemical name for baking soda), dissociates in this way:</p><div class="figure"><figure> $$NaHCO_3 \rightarrow Na^+ + HCO_3$$ <figcaption><strong>Equation 10</strong></figcaption> </figure></div></p><p>Notice that the sodium bicarbonate <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reaction</mark> only goes in the forward direction and doesn’t involve <mark class="term" data-term="Hydronium ion" data-term-def="A positively charged water molecule that has taken on an additional proton, to be H-3O+." data-term-url="/en/glossary/view/Hydronium+ion/12076">hydronium ions</mark> because it isn’t actually an acid-base reaction, just the dissolving of a <mark class="term" data-term="solid" data-term-def="A collection of atoms or molecules that are held together so that, under constant conditions, they maintain a defined shape and&hellip;" data-term-url="/en/glossary/view/solid/7571">solid</mark>. The net effect of adding the sodium bicarbonate is really adding bicarbonate <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ions</mark>, in other words, the conjugate <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark> of carbonic <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark>.</p><p>If carbonic <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> (or any other acid) is added to this <mark class="term" data-term="solution" data-term-def="A mixture of more than one substance with properties that do not vary within the sample. Commonly used to describe a&hellip;" data-term-url="/en/glossary/view/solution/1571">solution</mark>,the extra bicarbonate <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ions</mark> are available to <mark class="term" data-term="absorb" data-term-def="Take in or soak up (energy, liquids, or other substances), usually gradually, through a chemical or physical action." data-term-url="/en/glossary/view/absorb/11219">absorb</mark> the acidic <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">protons</mark>, minimizing changes in <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark>. Without those extra bicarbonate <mark class="term" data-term="ion" data-term-url="/en/glossary/view/ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;">ions</mark>, the H+ from the additional <mark class="term" data-term="carbonic acid" data-term-def="The weak acid formed when CO<sub>2</sub> dissolves in water." data-term-url="/en/glossary/view/carbonic+acid/2192">carbonic acid</mark> would be released into solution until the <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">system</mark> reached <mark class="term" data-term="equilibrium" data-term-def="A state of balance between opposing forces; a state of balance in which opposing forces cancel one another. A state in&hellip;" data-term-url="/en/glossary/view/equilibrium/8680">equilibrium</mark>, with a higher [H+]. Instead, the bicarbonate added by the baking soda absorbed those ions, forming more carbonic acid while maintaining a stable pH.</p><p>Sörenson described this <mark class="term" data-term="process" data-term-def="Method, procedure; series of actions or steps." data-term-url="/en/glossary/view/process/8256">process</mark> as “buffering,” and called the <mark class="term" data-term="solution" data-term-def="A mixture of more than one substance with properties that do not vary within the sample. Commonly used to describe a&hellip;" data-term-url="/en/glossary/view/solution/1571">solution</mark> of weak <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acid</mark> plus conjugate <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">base</mark> a <mark class="term" data-term="buffer" data-term-def="An aqueous solution containing a weak acid and its conjugate base that moderates pH changes when acid or base is added.&hellip;" data-term-url="/en/glossary/view/buffer/1576">buffer</mark>. He likened it to adding shock absorbers on a train. The springs in the shock absorbers <mark class="term" data-term="absorb" data-term-def="Take in or soak up (energy, liquids, or other substances), usually gradually, through a chemical or physical action." data-term-url="/en/glossary/view/absorb/11219">absorb</mark> the train’s up and down bounces, giving passengers a smoother ride. Similarly, the <mark class="term" data-term="Conjugate base" data-term-def="In an acid-base reaction, the conjugate base is the species that results when the original acid donates a proton to the&hellip;" data-term-url="/en/glossary/view/Conjugate+base/12075">conjugate base</mark> of a <mark class="term" data-term="Weak acid" data-term-def="An acid that partially dissociates into its constituent ions in water." data-term-url="/en/glossary/view/Weak+acid/12079">weak acid</mark> acts as a “proton absorber, able to absorb the addition of new <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">protons</mark> and keep the <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark> within a certain range. Buffers using a <mark class="term" data-term="Weak base" data-term-def="A base that partially dissociates into its constituent ions in water." data-term-url="/en/glossary/view/Weak+base/12080">weak base</mark> and its <mark class="term" data-term="Conjugate acid" data-term-def="Conjugate acid: In an acid-base reaction, the conjugate acid is the species that results when the original base accepts a proton&hellip;" data-term-url="/en/glossary/view/Conjugate+acid/12074">conjugate acid</mark> <mark class="term" data-term="work" data-term-def="A process that occurs when a force acts over a distance, as when an object is moved. Work equals the multiple&hellip;" data-term-url="/en/glossary/view/work/1502">work</mark> in the same way. </p><div class="figure"><figure> <a href="https://visionlearning.com/images/figure-images/272-f-2x.png" title=""> <span class="fa fa-search-plus"></span> <img src="https://visionlearning.com/images/figure-images/272-f.png" alt=""> </a> <figcaption> <strong>Figure 6</strong>: Carbonic Acid Equilibrium </figcaption> </figure></div><p>When Henderson read SÃ¶rensonâs description of this concept, he had his explanation of how the bicarbonate system maintains blood pH: bicarbonate ions in the blood are able to absorb excess protons. In fact, there are bicarbonate ions in all the fluids in your body. At the beginning of this module, you learned that your body is always producing carbon dioxide as a waste product of metabolism, and some of it combines with water to create carbonic acid. That carbonic acid dissociates when it combines with water in your cells and body fluids. The equilibrium works like this:<div class="figure"><figure> $$CO_2 + H_2O \leftrightarrow H_2CO_3 \leftrightarrow {HCO_3}^- + H^+$$ <figcaption><strong>Equation 11</strong></figcaption> </figure></div></p><p>Your kidneys regulate the <mark class="term" data-term="concentration" data-term-def="The amount of one substance in relation to other components within a given area." data-term-url="/en/glossary/view/concentration/8733">concentration</mark> of bicarbonate in your blood, making sure there are always enough of these <mark class="term" data-term="ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;" data-term-url="/en/glossary/view/ion/853">ions</mark>. This role of the kidneys explains why people with kidney disease and diabetes are susceptible to acidosis. If the kidneys aren’t functioning properly, they fail to retain bicarbonate <mark class="term" data-term="ion" data-term-url="/en/glossary/view/ion" data-term-def="An atom or molecule that has acquired an electrical charge by either gaining or losing electrons. A cation is an ion&hellip;">ions</mark>, and so the body loses some of its buffering capacity. </p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc12265"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">A ________ acid does not completely break down into ions when in solution.</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-12265-0-option-a" name="quiz-option-12265" type="radio" value="strong" > <span class="option__label"> <span class="screen-reader-only">a.</span> strong </span> </label> <span class="quiz__response" id="response-12265-0"> <strong>Incorrect.</strong> </span> </div> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-12265-1-option-b" name="quiz-option-12265" type="radio" value="weak" > <span class="option__label"> <span class="screen-reader-only">b.</span> weak </span> </label> <span class="quiz__response" id="response-12265-1"> <strong>Correct!</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_5"> <h2>Conclusion</h2><p>The bicarbonate <mark class="term" data-term="buffer" data-term-def="An aqueous solution containing a weak acid and its conjugate base that moderates pH changes when acid or base is added.&hellip;" data-term-url="/en/glossary/view/buffer/1576">buffer</mark> <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">system</mark> offers an elegant example of the potential of acid-base chemistry. Strong <mark class="term" data-term="acid" data-term-def="Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different&hellip;" data-term-url="/en/glossary/view/acid/1573">acids</mark> and <mark class="term" data-term="base" data-term-def="Generally, a substance that reacts with acids to form a salt, several different definitions of bases have been proposed by different&hellip;" data-term-url="/en/glossary/view/base/1574">bases</mark>, which completely <mark class="term" data-term="dissociate" data-term-def="The breaking apart of a molecule, especially in the presence of heat or a polar solvent. For example, the ionic&hellip;" data-term-url="/en/glossary/view/dissociate/1561">dissociate</mark> in water, can induce burns and corrode metal. <mark class="term" data-term="Weak acid" data-term-def="An acid that partially dissociates into its constituent ions in water." data-term-url="/en/glossary/view/Weak+acid/12079">Weak acids</mark>, however, can produce a wide range of pH’s, and are important in any system that requires a <mark class="term" data-term="pH" data-term-def="A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H<sup>+</sup>]. pH&hellip;" data-term-url="/en/glossary/view/pH/1577">pH</mark> closer to the middle of the <mark class="term" data-term="spectrum" data-term-def="(plural: <b>spectra</b>) A continuing range such as of color or frequency; a series of colors arranged by wavelength as in a rainbow." data-term-url="/en/glossary/view/spectrum/8261">spectrum</mark>. The combination of a weak acid with its <mark class="term" data-term="Conjugate base" data-term-def="In an acid-base reaction, the conjugate base is the species that results when the original acid donates a proton to the&hellip;" data-term-url="/en/glossary/view/Conjugate+base/12075">conjugate base</mark> can create a buffer to mitigate the effects of additional <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">protons</mark> from other acids or <mark class="term" data-term="reaction" data-term-def="A chemical change when substances come into contact with each other." data-term-url="/en/glossary/view/reaction/8263">reactions</mark> in the <mark class="term" data-term="solution" data-term-def="A mixture of more than one substance with properties that do not vary within the sample. Commonly used to describe a&hellip;" data-term-url="/en/glossary/view/solution/1571">solution</mark>. This buffering capability is central to the success of any <mark class="term" data-term="process" data-term-def="Method, procedure; series of actions or steps." data-term-url="/en/glossary/view/process/8256">process</mark> that requires maintaining a steady pH, such as dying fabrics, manufacturing drugs, counteracting acidity in shampoo and baby lotion, and even keeping your pizza from giving you acidosis.</p> </div> </section> <hr class="border-color-dark" /> <footer class="module__footer"> <p class="citation"> <em> Robin Marks, M.A. “Acids and Bases II” Visionlearning Vol. CHE-5 (1), 2020. </em> </p> </footer> </div>   </div>  <div class="order-1 order-2--lg module__tools"> <div class="narrow margin-x-auto position-sticky-top font-size-md"> <div class="padding-2 border-radius box-shadow-1--lg"> <div class="tabs" role="tablist"> <nav> <button class="button button--icon-label" id="tab-button-in-this-module" aria-label="Table of Contents" aria-controls="tab-panel-module__tools" aria-selected="true" role="tab"> <span class="icon icon-list" aria-hidden="true"></span> <span class="button__text">Contents</span> </button> <button class="button button--icon-label" id="tab-button-toggle-terms" aria-controls="tab-panel-toggle-terms" aria-selected="false" role="tab"> <span class="icon icon-glossary-highlight"></span> <span class="button__text">Glossary Terms</span> </button> </nav> <hr class="divider" /> <div class="tabs__panel shown" id="tab-panel-module__tools" aria-labelledby="tab-button-module__tools" role="tabpanel"> <p class="font-weight-bold margin-bottom-1"> Table of Contents </p> <div class="table-of-contents" id="module-toc"> <ul> <li><a href="/en/library/chemistry/1/acids-and-bases-ii/272#toc_1">Equilibrium: A Balancing Act</a> </li> <li><a href="/en/library/chemistry/1/acids-and-bases-ii/272#toc_2">Conjugate Acids, Bases & Amphoteric Molecules</a> </li> <li><a href="/en/library/chemistry/1/acids-and-bases-ii/272#toc_3">Strong versus weak acids</a> </li> <li><a href="/en/library/chemistry/1/acids-and-bases-ii/272#toc_4">Weak acids and their conjugate bases make good buffers</a> </li> <li><a href="/en/library/chemistry/1/acids-and-bases-ii/272#toc_5">Conclusion</a> </li> </ul> </div> </div>   <div class="tabs__panel" id="tab-panel-toggle-terms" aria-labelledby="tab-button-toggle-terms" role="tabpanel"> <div class="reading-toggle"> <div class="reading-toggle__switch"> <div class="form-entry__option__switch"> <label> <input type="checkbox" name="termsToggleSwitch" id="terms-toggle-switch" /> <span class="switch__slider"></span> <span class="option__label text-decoration-none font-size-md"> Highlight Glossary Terms </span> </label> </div> </div> <div class="reading-toggle__help"> <p> <em> Activate glossary term highlighting to easily identify key terms within the module. 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Acids and Bases II | Chemistry | Visionlearning