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/elements menu--> <div class="pure-g"> <div class="pure-u-1"> <div class="pure-menu pure-menu-open pure-menu-horizontal centre" role="navigation" style="background: #000 url(../_media/elements/discharge/H.png) repeat-y center; background-size:contain;"> <span><a class="pure-menu-heading" href="https://winter.group.shef.ac.uk/webelements/"><img height="30" src="../_media/icons/logo_60.png" alt="WebElements logo"></a> <a class="white" href="./">Hydrogen - <sub>1</sub>H</a>&nbsp;&nbsp;<audio id="myAudio_f"> <source src="../_media/elements/snds_f/H.mp3" type="audio/mpeg">Your user agent does not support the HTML5 Audio element. </audio> <button class="pure-button s_button" style=" display: inline;" type="button" onclick="audf_play_pause()"> 🔊&nbsp; </button> <script> function audf_play_pause() { var myAudiof = document.getElementById("myAudio_f"); if (myAudiof.paused) { myAudiof.play(); } else { myAudiof.pause(); }} </script></span> </div> </div> </div> <div id="main"> <!-- element specific content--> <div class="pure-u-1 pure-u-sm-1-1"> <div class="pure-menu pure-menu-horizontal pure-menu-scrollable"> <a href="#" class="pure-menu-link pure-menu-heading">▸▸</a> <ul class="pure-menu-list"> <li class="pure-menu-item">🇬🇧&nbsp;Hydrogen</li> <li class="pure-menu-item">🇺🇦&nbsp;Водень</li> <li class="pure-menu-item">🇨🇳&nbsp;氫</li> <li class="pure-menu-item">🇳🇱&nbsp;Waterstof</li> <li class="pure-menu-item">🇫🇷&nbsp;Hydrog&egrave;ne</li> <li class="pure-menu-item">🇩🇪&nbsp;Wasserstoff</li> <li class="pure-menu-item">🇮🇱&nbsp;מימן</li> <li class="pure-menu-item">🇮🇹&nbsp;Idrogeno</li> <li class="pure-menu-item">🇯🇵&nbsp;水素</li> <li class="pure-menu-item">🇵🇹&nbsp;Hidrog&ecirc;nio</li> <li class="pure-menu-item">🇪🇸&nbsp;Hidr&oacute;geno</li> <li class="pure-menu-item">🇸🇪&nbsp;V&auml;te</li> <li class="pure-menu-item">🇷🇺&nbsp;Водород</li> </ul> </div> </div> <div class="pure-g"> <div class="pure-u-1 pure-u-sm-1-1"> <div class="google_navbar_positioning"> <form action="https://www.google.com" id="cse-search-box"> <div> <input type="hidden" name="cx" value="partner-pub-9334432533380510:6223510783"> <input type="hidden" name="ie" value="UTF-8"> <input type="text" name="q" size="28"> <input type="submit" name="sa" value="Search"> </div> </form> <script> </script> </div> </div> </div> <main> <div class="pure-g"> <div class="pure-u-1 pure-u-sm-1-1"> <h1 class="s">Hydrogen - <sub><small>1</small></sub>H: the essentials</h1> <div class="pure-menu pure-menu-horizontal pure-menu-scrollable"> <ul class="pure-menu-list z_menu"> <li class="pure-menu-item s"><a href="../hydrogen/" class="pure-menu-link">▸▸ H Essentials</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/physics.html">Physical properties</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/atoms.html">Electron shell data</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/atom_sizes.html">Atom sizes</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/electronegativity.html">Electronegativity</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/isotopes.html" >Isotopes and NMR</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/crystal_structure.html">Crystal structure</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/thermochemistry.html">Thermochemistry</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/history.html">History</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/uses.html">Uses</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/geology.html">Geology</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/biology.html">Biology</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/compounds.html">Binary compounds</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/compound_properties.html" >Compound properties</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/chemistry.html">Element reactions</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../hydrogen/contents.html">List all H properties</a></li> </ul> </div> </div> </div> <!-- element specific content--> <div class="pure-g"> <div class="pure-u-1 pure-u-sm-1-2"> <!-- Basic data 1/2 columns --> <ul class="ul_facts_table"> <li><a href="../periodicity/name_english/" title="Element names">Name</a>: hydrogen</li> <li><a href="../periodicity/name_english/" title="Element symbol">Symbol</a>: H</li> <li><a href="../periodicity/atomic_number/" title="Element atomic number">Atomic number</a>: 1 </li> <li><a href="../periodicity/atomic_weight/" title="Element atomic weight">Relative atomic mass (<i>A</i><sub>r</sub>)</a>: 1.008 range: [1.00784, 1.00811] m [see notes <a href="../periodicity/atomic_weight/index.html#footnote_g">g</a> <a href="../periodicity/atomic_weight/index.html#footnote_m">m</a> <a href="../periodicity/atomic_weight/index.html#footnote_r">r</a>] </li> <li><a href="../periodicity/standard_state/" title="Element standard state">Standard state</a>: gas at 298 K</li> <li><a href="../periodicity/standard_state/" title="Element colour">Appearance</a>: colourless</li> <li><a href="../periodicity/classification/" title="Classification of hydrogen as metal, non-metal, or semi-metal">Classification</a>: Non-metallic </li> </ul> </div> <div class="pure-u-1 pure-u-sm-1-2"> <ul class="ul_facts_table"> <li><a href="../periodicity/group_number/" title="The group within which hydrogen is located">Group in periodic table</a>: 1</li> <li><a href="../periodicity/group_number/" title="The name of the group (if there is one) within which hydrogen is located">Group name</a>: (none)</li> <li><a href="../periodicity/group_number/" title="The period within which hydrogen is located">Period in periodic table</a>: 1</li> <li><a href="../periodicity/group_number/" title="The block within which hydrogen is located">Block in periodic table</a>: s</li> <li><a href="../periodicity/electron_shell_structure/" title="Shell structure">Shell structure</a>: 1 </li> <li><a href="../periodicity/cas_registry_id/" title="Chemical Abstract Service (CAS) Registry numbers for the elements">CAS Registry</a>: 1333-74-0</li> </ul> </div> </div> <p class="p_first"> Hydrogen atoms have 1 electrons and the <strong><a href="../periodicity/electron_shell_structure/">shell structure</a></strong> is&nbsp;1. The <strong> <a href="../periodicity/electronic_configuration/">ground state electronic configuration of neutral hydrogen is</a></strong>&nbsp;<strong>1s</strong><sup>1</sup> and the <strong><a href="../periodicity/term_symbol/">term symbol of hydrogen </a> is</strong>&nbsp;<sup>2</sup><strong>S</strong><sub>1/2</sub>. </p> <h2 class="s">Hydrogen: description&nbsp;&nbsp;<audio id="myAudio_desc"> <source src="../_media/elements/snds_description/H.mp3" type="audio/mpeg">Your user agent does not support the HTML5 Audio element. </audio> <button class="pure-button s_button" style="display: inline;" type="button" onclick="auddesc_play_pause()">&#x1f50a;</button> <script> function auddesc_play_pause() { var myAudiodesc = document.getElementById("myAudio_desc"); if (myAudiodesc.paused) { myAudiodesc.play(); } else { myAudiodesc.pause(); }} </script> </h2> <div class="pure-g"> <div class="pure-u-1 pure-u-sm-1-1"> <p class="p_first">Note that while hydrogen is normally shown at the top of the Group 1 elements in the periodic table, the term "alkaline metal" refers to the Group 1 elements from lithium downwards and not hydrogen.</p> <p>Hydrogen is the lightest element. It is by far the most abundant element in the universe and makes up about about 90% of the universe by weight. It is also the most abundant element in the earth's sun.</p> <p class="pure-img"><img src="../_media/elements/pictures/hydrogen/1_H.jpg" alt="picture of the sun in which hydrogen is the most abundant element" /></p> <p>Hydrogen as water (H<sub>2</sub>O) is absolutely essential to life and it is present in all organic compounds. Hydrogen is the lightest gas. Hydrogen gas was used in lighter-than-air balloons for transport but is far too dangerous because of the fire risk (Hindenburg). It burns in air to form only water as waste product and if hydrogen could be made on sufficient scale from other than fossil fuels then there might be a possibility of a hydrogen economy.</p> </div> </div> <!-- Row Basic data 1/2 columns --> <div class="pure-g display_table"> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: physical properties</h2> <ul class="spark_table_list"> <li><a href="../periodicity/density/" title="view definition and images showing periodicity for density of elemental solids"><img alt="Density of the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" /> Density of solid</a>: 88&nbsp;kg m<sup>-3</sup></li> <li><a href="../periodicity/molar_volume/" title="view definition and images showing periodicity for molar volumes of the elements"><img alt="Molar volume of the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" /> Molar volume</a>: 11.42&nbsp;cm<sup>3</sup></li> <li><a href="../periodicity/thermal_conduct/" title="show definition and view pictures showing periodicity of thermal conductivity in the periodic table"><img alt="Thermal conductivity of the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" /> Thermal conductivity</a>: 0.1805&nbsp;W&nbsp;m<sup>&#8209;1</sup>&nbsp;K<sup>&#8209;1</sup></li> </ul> <p><a class="pure-button" href="./physics.html">More physical properties...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: heat properties</h2> <ul class="spark_table_list"> <li><a href="../periodicity/melting_point/" title="show definition and view pictures showing periodicity of melting point in the periodic table"><img alt="Melting point on a miniature periodic table spark table" src="data:image/png;base64,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" /> Melting point</a>: 14.01 [&#8209;259.14&nbsp;&#176;C (&#8209;434.45&nbsp;&#176;F)]&nbsp;K</li> <li><a href="../periodicity/boiling_point/" title="show definition and view pictures showing periodicity of boiling point in the periodic table"><img alt="Boiling point on a miniature periodic table spark table" src="data:image/png;base64,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" /> Boiling point</a>: 20.28 [&#8209;252.87&nbsp;&#176;C (&#8209;423.17&nbsp;&#176;F)]&nbsp;K</li> <li><a href="../periodicity/enthalpy_fusion/" title="show definition and view pictures showing periodicity of fusion enthalpy in the periodic table"><img alt="Enthalpy of fusion on a miniature periodic table spark table" src="data:image/png;base64,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" /> Enthalpy of fusion</a>: 20.5&nbsp;kJ mol<sup>-1</sup></li> </ul> <p><a class="pure-button" href="./thermochemistry.html">More thermochemical properties...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: atom sizes</h2> <ul class="spark_table_list"> <li><a href="../periodicity/atom_radius_emp/" title="View atomic radius data for the elements"><img alt="Atomic radius (empirical) of the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" /> Atomic radius (empirical)</a>: 25&nbsp;pm</li> <li><a href="../periodicity/rad_cov_single/" title="View molecular single bond covalent radii data for the elements"><img alt="Covalent (single bond) radius on a periodic table spark table" src="data:image/png;base64,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" /> Molecular single bond covalent radius</a>: 32 (coordination number 1)&nbsp;ppm</li> <li><a href="../periodicity/van_der_waals_rad/" title="View van der Waals' radius data for the elements"><img alt="van der Waals radius on a periodic table spark table" src="data:image/png;base64,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" /> van der Waals radius</a>: 120&nbsp;ppm</li> </ul> <p><a class="pure-button" href="./atom_sizes.html">More atomc size properties...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: electronegativities</h2> <ul class="spark_table_list"> <li><a href="../periodicity/eneg_pauling/" title="View definition and pictures showing periodicity of Pauling electronegativity"><img alt="Pauling electronegativity of the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" /> Pauling electronegativity</a>: 2.20 (Pauling units)</li> <li><a href="../periodicity/eneg_allred_rochow/" title="View definition and pictures showing periodicity of Allred Rochow electronegativity"><img alt="Allred-Rochow electronegativity of the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" />Allred Rochow electronegativity</a>: 2.20 (Pauling units)</li> <li><a href="../periodicity/eneg_mulliken_j/" title="View definition and pictures showing periodicity of Mulliken-Jaffe electronegativity"><img alt="Mulliken-Jaffe electronegativity of the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" />Mulliken-Jaffe electronegativity</a>: 2.25 (s orbital)</li> </ul> <p><a class="pure-button" href="./electronegativity.html">More electronegativity properties...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: orbital properties</h2> <ul class="spark_table_list"> <li><a href="../periodicity/ionis_energy_1/" title="View definition and pictures showing first ionisation energies"><img alt="First ionization energy the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" /> First ionisation energy</a>: 1312.05 (calculated)&nbsp;kJ&nbsp;mol<sup>&#8209;1</sup></li> <li><a href="../periodicity/ionis_energy_2/" title="View definition and pictures showing second ionisation energies"><img alt="Second ionization energy the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" /> Second ionisation energy</a>: (no data)&nbsp;kJ&nbsp;mol<sup>&#8209;1</sup></li> <li><a href="../periodicity/ionis_energy_3/" title="View definition and pictures showing third ionisation energies"><img alt="Third ionization energy the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" /> Third ionisation energy</a>: (no data)&nbsp;kJ&nbsp;mol<sup>&#8209;1</sup></li> </ul> <p><a class="pure-button" href="./atoms.html">More orbital properties...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: abundances</h2> <ul class="spark_table_list"> <li><a href="../periodicity/abund_universe/" title="Definitions and pictures showing periodicity of element abundances in the universe"><img alt="Chemical elements abundance by weight in the universe on a miniature periodic table spark table" src="data:image/png;base64,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" />Universe</a>: 750000000&nbsp;ppb by weight</li> <li><a href="../periodicity/abund_crust/" title="Definitions and pictures showing periodicity of element abundances in the earth&#39;s crust"><img alt="Chemical elements abundance by weight in the earth&#39;s crust on a miniature periodic table spark table" src="data:image/png;base64,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" />Crustal rocks</a>: 1500000&nbsp;ppb by weight</li> <li><a href="../periodicity/abund_humans/" title="Abundance in humans of the chemical elements displayed graphically"><img alt="Chemical elements abundance by weight in humans on a miniature periodic table spark table" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAFAAAAAwCAIAAAF+gFo2AAAABGdBTUEAANkDQtZPoQAAAAlwSFlzAAALEwAACxMBAJqcGAAAACR0RVh0U29mdHdhcmUAUXVpY2tUaW1lIDcuNS41IChNYWMgT1MgWCkADDxZHwAAAAd0SU1FB9kBEhYYBzpBg9sAAAJOSURBVHic7ZpNloIwDIBbH8+VN5gb4DXwBu69mp4DNh7Cm7iC92QikRJaKkFK67N8ixkobZo0TfozI8QodV3rJeczFOV5vnm+lSU81YTi7080bSS2LoqCts6yTCsZRuIvEG62OBwOH6gN3O+v8vrx0NRWr/A1EfLZveoVNKCvDM1BmvmhU7u+3ViiCCixGfI0Na3TeBlVlmCoqpxQYTiq5th25deraE3vrOK6jwBmS80MZrNJ3SyEF1dBRMHUJLN2M6G700lst+LxUAUJihVVhZooH2qgI7WvTWOY/iCSTgZjkggSykpET238Nhr+6nVj1h5UeLTaZGZNzwFX2Qb8x4DQ+CA6ppI34HM71mmKkTUaXO95ZUmIPgxAjMG2nNZMbCJmAZELVNXzJ4nfoY5RnaYqnaNTZxoNnPdt246blRCzAW1GA/99NNJuzPqmEtahps04XTJzid7xYFZkYgp1nKncIs0ifgLkY67krOUta3CuzYpXwi0S3gm2OgWzONiyGNxi7+txcIu9bwSCW2yw9A4ktMX+tz7BLI6P797sLUGwXeY6q1dWHNHLW/QoIfd778q4hGZfmjWjyx79/RacnlroMUfKgQXMA72j1uXSPR+P3fNuRxuoR9sOKHIPfzN49kTwBIpYzqE2IvcwjRkyirb95tLXfLY4nNNv5B6m2ZjcCVDo6NpO+nOux23e48jneD5yDzOwja4rr86Rs94+DNDzMP/u0S0cz7j6s1l0Hl75dVjHoCVu9paA809e0cWws9OSq7V0aaLz8Mqv8w9SY7gt6Xpm3wAAAABJRU5ErkJggg==" />Human</a>: 100000000&nbsp;ppb by weight</li> </ul> <p><a class="pure-button" href="./geology.html">More geological data...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: crystal structure</h2> <figure><img class="pure-img" src="../_media/elements/crystal_structure_image/H-sf.jpg" alt="H crystal structure"><figcaption>The solid state structure of hydrogen is: hcp (hexagonal close-packed)..</figcaption></figure> <p><a class="pure-button" href="./crystal_structure.html">More crystallographic data...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: biological data</h2> <ul class="spark_table_list"> <li><a href="../periodicity/abund_humans/" title="View definition and pictures showing human abundance by weight"><img alt="Human abundance by weight of the chemical elements on a miniature periodic table spark table" src="data:image/png;base64,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" /> Human abundance by weight</a>: 100000000&nbsp;ppb by weight</li> </ul> <p class="p_first">Hydrogen makes up two of the three atoms in water and water is absolutely essential to life. Hydrogen is present in all organic compounds. A form of water in which both hydrogen atoms are replaced by deuterium (<sup>2</sup>H, or D) is called "heavy water" (D<sub>2</sub>O) and is toxic to mammals. Some bacteria are known to metabolise molecular hydrogen (H<sub>2</sub>).</p> <p><a class="pure-button" href="./biology.html">More biological data...</a></p> <div> <script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script> <!-- Elements_body 300_250 --> <ins class="adsbygoogle" style="display:inline-block;width:300px;height:250px" data-ad-client="ca-pub-9334432533380510" data-ad-slot="2897369985"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: uses</h2> <p><a class="pure-button" href="./uses.html">Uses...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: reactions</h2> <p> Reactions of hydrogen as the element with air, water, halogens, acids, and bases where known. </p> <p><a class="pure-button" href="./chemistry.html">View reactions of hydrogen...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: binary compounds</h2> <p> Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of hydrogen where known. </p> <p><a class="pure-button" href="./compounds.html">View binary compounds...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: compound properties</h2> <p> Bond strengths; lattice energies of hydrogen halides, hydrides, oxides (where known); and reduction potentials where known. </p> <p><a class="pure-button" href="./compound_properties.html">View compound properties...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: history</h2> <strong>Hydrogen</strong> was <a href="../periodicity/discovery/" title="Further information on element discoveries">discovered</a> by Henry Cavendish in 1766 at London, England. <a href="../periodicity/discovery/" title="Further information on element discoveries">Origin of name</a>: from the Greek words "<em>hydro</em>" and <em>"genes</em>" meaning "<em>water</em>" and "<em>generator</em>". <p><a class="pure-button" href="./history.html">More history...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-2"> <h2 class="s">Hydrogen: isotopes</h2> <div><figure><img class="pure-img" src="../_media/elements/isotopes/isotope_abundance_H.png" alt="Isotope abundances of hydrogen" /><figcaption>Isotope abundances of hydrogen with the most intense signal set to 100%.</figcaption></figure></div> <p class="p_first">The Hydrogen isotope H-2, also known as deuterium, is used in a variety of applications. Deuterium is used extensively in organic chemistry in order to study chemical reactions. It is also used in vitamin research. Deuterium in the form of H<sub>2</sub>O, known as heavy water, is used as a moderator in CANDU nuclear reactors, in NMR studies and in studies into human metabolism. Heavy water is also applied in the Sudbury Neutrino Observatory where it is used to study the behavior of neutrinos.</p> <p><a class="pure-button" href="./isotopes.html">More isotope and NMR data...</a></p> </div> <div class="pure-u-1 pure-u-md-1-1 pure-u-lg-1-1"> <h2 class="s">Hydrogen: isolation</h2> <p class="p_first"> <a href="../periodicity/isolation/" title="literature sources referring to isolation of pure hydrogen">Isolation</a>: in the laboratory, small amounts of hydrogen gas may be made by the reaction of calcium hydride with water.</p> <p class="equation">CaH<sub>2</sub> + 2H<sub>2</sub>O &rarr; Ca(OH)<sub>2</sub> + 2H<sub>2</sub></p> <p>This is quite efficient in the sense that 50% of the hydrogen produced comes from water. Another very convenient laboratory scale experiment follows Boyle's early synthesis, the reaction of iron filings with dilute sulphuric acid.</p> <p class="equation">Fe + H<sub>2</sub>SO<sub>4</sub> &rarr; FeSO<sub>4</sub> + H<sub>2</sub></p> <p>There are many industrial methods for the production of hydrogen and that used will depend upon local factors such as the quantity required and the raw materials to hand. Two processes in use involve heating coke with steam in the water gas shift reaction or hydrocarbons such as methane with steam.</p> <p class="equation">CH<sub>4</sub> + H<sub>2</sub>O (1100&#176;C) &rarr; CO + 3H<sub>2</sub></p> <p class="equation">C(coke) + H<sub>2</sub>O (1000&#176;C) &rarr; CO + H<sub>2</sub></p> <p>In both these cases, further hydrogen may be made by passing the CO and steam over hot (400&#176;C) iron oxide or cobalt oxide.</p> <p class="equation">CO + H<sub>2</sub>O &rarr; CO<sub>2</sub> + H<sub>2</sub></p> </div> </div> <!-- /element specific content--> </main> <div id="footer"><!-- Footer div --> <footer> <div class="footer"> <div class="pure-g"> <div class="pure-u-1-2 pure-u-sm-1-2 pure-u-lg-1-4 pure-menu custom-restricted-width"> <ul class="pure-menu-list"> <li class="pure-menu-heading footer_h">Key properties</li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/eneg_pauling/">Electronegativity </a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/melting_point/">Melting point</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/density/">Density </a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/molar_volume/">Molar volume</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/ionis_energy_1/">Ionization energy (1st)</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/covalent_radius/">Covalent radius</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/metallic_radius/">Metallic radius</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/abund_crust/">Abundance: earth's crust</a></li> </ul> </div> <div class="pure-u-1-2 pure-u-sm-1-2 pure-u-lg-1-4 pure-menu custom-restricted-width"> <ul class="pure-menu-list"> <li class="pure-menu-heading footer_h">Shop</li> <li class="pure-menu-item">Sorry, shop closed</li> </ul> </div> <div class="pure-u-1-2 pure-u-sm-1-2 pure-u-lg-1-4 pure-menu custom-restricted-width"> <ul class="pure-menu-list"> <li class="pure-menu-heading footer_h">Social</li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.facebook.com/webelements.periodic.table">Facebook</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://twitter.com/periodic_table">Twitter</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.pinterest.com/periodictable/">Pinterest</a></li> </ul> </div> <div class="pure-u-1-2 pure-u-sm-1-2 pure-u-lg-1-4 pure-menu custom-restricted-width"> <ul class="pure-menu-list"> <li class="pure-menu-heading footer_h">Administration</li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/nexus/your-privacy/" title="Your privacy">Privacy</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/nexus/about-webelements/" title="About WebElements">About</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/nexus/webelements-and-copyright/" title="Copyright information about WebElements">Copyright</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/nexus/acknowledgements/" title="Acknowledgements">Thanks...</a></li> </ul> </div> </div> </div> <address> <p> <a href="https://www.webelements.com/"><img class="logo_m" src="../_media/icons/logo_60.png" alt="WebElements home" /></a><br /> <strong>WebElements:</strong> THE periodic table on the WWW [<a href="https://www.webelements.com/">www.webelements.com</a>]<br /> <a href="https://www.webelements.com/nexus/webelements-and-copyright/">Copyright </a> 1993-2024 <a href="https://winter.group.shef.ac.uk/">Mark Winter</a> [ <a href="https://www.sheffield.ac.uk/chemistry/">The University of Sheffield </a> and WebElements Ltd, UK]. 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