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</header> </div> <div class="mw-page-container"> <div class="mw-page-container-inner"> <div class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Sommaire" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Sommaire</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">déplacer vers la barre latérale</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">masquer</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">Début</div> </a> </li> <li id="toc-Masse_moléculaire_(absolue)" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Masse_moléculaire_(absolue)"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>Masse moléculaire (absolue)</span> </div> </a> <ul id="toc-Masse_moléculaire_(absolue)-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Masse_moléculaire_(relative)" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Masse_moléculaire_(relative)"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Masse moléculaire (relative)</span> </div> </a> <ul id="toc-Masse_moléculaire_(relative)-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Masse_moléculaire_des_polymères" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Masse_moléculaire_des_polymères"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Masse moléculaire des polymères</span> </div> </a> <ul id="toc-Masse_moléculaire_des_polymères-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Masse_moléculaire_des_protéines" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Masse_moléculaire_des_protéines"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Masse moléculaire des protéines</span> </div> </a> <ul id="toc-Masse_moléculaire_des_protéines-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Détermination" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Détermination"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Détermination</span> </div> </a> <button aria-controls="toc-Détermination-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Afficher / masquer la sous-section Détermination</span> </button> <ul id="toc-Détermination-sublist" class="vector-toc-list"> <li id="toc-Spectrométrie_de_masse" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Spectrométrie_de_masse"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Spectrométrie de masse</span> </div> </a> <ul id="toc-Spectrométrie_de_masse-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Méthodes_hydrodynamiques" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Méthodes_hydrodynamiques"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>Méthodes hydrodynamiques</span> </div> </a> <ul id="toc-Méthodes_hydrodynamiques-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Diffusion_statique_de_la_lumière" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Diffusion_statique_de_la_lumière"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.3</span> <span>Diffusion statique de la lumière</span> </div> </a> <ul id="toc-Diffusion_statique_de_la_lumière-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Articles_connexes" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Articles_connexes"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Articles connexes</span> </div> </a> <ul id="toc-Articles_connexes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Références" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Références"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Références</span> </div> </a> <ul id="toc-Références-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Sommaire" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" title="Table des matières" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Basculer la table des matières" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Basculer la table des matières</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Masse moléculaire</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Aller à un article dans une autre langue. Disponible en 62 langues." > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-62" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">62 langues</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%83%D8%AA%D9%84%D8%A9_%D8%AC%D8%B2%D9%8A%D8%A6%D9%8A%D8%A9" title="كتلة جزيئية – arabe" lang="ar" hreflang="ar" data-title="كتلة جزيئية" data-language-autonym="العربية" data-language-local-name="arabe" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%90%D0%B4%D0%BD%D0%BE%D1%81%D0%BD%D0%B0%D1%8F_%D0%BC%D0%B0%D0%BB%D0%B5%D0%BA%D1%83%D0%BB%D1%8F%D1%80%D0%BD%D0%B0%D1%8F_%D0%BC%D0%B0%D1%81%D0%B0" title="Адносная малекулярная маса – biélorusse" lang="be" hreflang="be" data-title="Адносная малекулярная маса" data-language-autonym="Беларуская" data-language-local-name="biélorusse" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%90%D0%B4%D0%BD%D0%BE%D1%81%D0%BD%D0%B0%D1%8F_%D0%BC%D0%B0%D0%BB%D0%B5%D0%BA%D1%83%D0%BB%D1%8F%D1%80%D0%BD%D0%B0%D1%8F_%D0%BC%D0%B0%D1%81%D0%B0" title="Адносная малекулярная маса – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Адносная малекулярная маса" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9C%D0%BE%D0%BB%D0%B5%D0%BA%D1%83%D0%BB%D0%BD%D0%B0_%D0%BC%D0%B0%D1%81%D0%B0" title="Молекулна маса – bulgare" lang="bg" hreflang="bg" data-title="Молекулна маса" data-language-autonym="Български" data-language-local-name="bulgare" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%86%E0%A6%A3%E0%A6%AC%E0%A6%BF%E0%A6%95_%E0%A6%AD%E0%A6%B0" title="আণবিক ভর – bengali" lang="bn" hreflang="bn" data-title="আণবিক ভর" data-language-autonym="বাংলা" data-language-local-name="bengali" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/Tolz_molekulel" title="Tolz molekulel – breton" lang="br" hreflang="br" data-title="Tolz molekulel" data-language-autonym="Brezhoneg" data-language-local-name="breton" class="interlanguage-link-target"><span>Brezhoneg</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Molekulska_masa" title="Molekulska masa – bosniaque" lang="bs" hreflang="bs" data-title="Molekulska masa" data-language-autonym="Bosanski" data-language-local-name="bosniaque" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Massa_molecular" title="Massa molecular – catalan" lang="ca" hreflang="ca" data-title="Massa molecular" data-language-autonym="Català" data-language-local-name="catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Molek%C3%BClmasse" title="Molekülmasse – allemand" lang="de" hreflang="de" data-title="Molekülmasse" data-language-autonym="Deutsch" data-language-local-name="allemand" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%9C%CE%BF%CF%81%CE%B9%CE%B1%CE%BA%CF%8C_%CE%B2%CE%AC%CF%81%CE%BF%CF%82" title="Μοριακό βάρος – grec" lang="el" hreflang="el" data-title="Μοριακό βάρος" data-language-autonym="Ελληνικά" data-language-local-name="grec" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-en mw-list-item"><a href="https://en.wikipedia.org/wiki/Molecular_mass" title="Molecular mass – anglais" lang="en" hreflang="en" data-title="Molecular mass" data-language-autonym="English" data-language-local-name="anglais" class="interlanguage-link-target"><span>English</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Molekula_maso" title="Molekula maso – espéranto" lang="eo" hreflang="eo" data-title="Molekula maso" data-language-autonym="Esperanto" data-language-local-name="espéranto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Masa_molecular" title="Masa molecular – espagnol" lang="es" hreflang="es" data-title="Masa molecular" data-language-autonym="Español" data-language-local-name="espagnol" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Molekulmass" title="Molekulmass – estonien" lang="et" hreflang="et" data-title="Molekulmass" data-language-autonym="Eesti" data-language-local-name="estonien" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Masa_molekular" title="Masa molekular – basque" lang="eu" hreflang="eu" data-title="Masa molekular" data-language-autonym="Euskara" data-language-local-name="basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AC%D8%B1%D9%85_%D9%85%D9%88%D9%84%DA%A9%D9%88%D9%84%DB%8C" title="جرم مولکولی – persan" lang="fa" hreflang="fa" data-title="جرم مولکولی" data-language-autonym="فارسی" data-language-local-name="persan" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Molekyylimassa" title="Molekyylimassa – finnois" lang="fi" hreflang="fi" data-title="Molekyylimassa" data-language-autonym="Suomi" data-language-local-name="finnois" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/Mais_mh%C3%B3il%C3%ADneach" title="Mais mhóilíneach – irlandais" lang="ga" hreflang="ga" data-title="Mais mhóilíneach" data-language-autonym="Gaeilge" data-language-local-name="irlandais" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Masa_molecular" title="Masa molecular – galicien" lang="gl" hreflang="gl" data-title="Masa molecular" data-language-autonym="Galego" data-language-local-name="galicien" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%9E%D7%A1%D7%94_%D7%9E%D7%95%D7%9C%D7%A7%D7%95%D7%9C%D7%A8%D7%99%D7%AA" title="מסה מולקולרית – hébreu" lang="he" hreflang="he" data-title="מסה מולקולרית" data-language-autonym="עברית" data-language-local-name="hébreu" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%85%E0%A4%A3%E0%A5%81_%E0%A4%AD%E0%A4%BE%E0%A4%B0" title="अणु भार – hindi" lang="hi" hreflang="hi" data-title="अणु भार" data-language-autonym="हिन्दी" data-language-local-name="hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Relativna_molekulska_masa" title="Relativna molekulska masa – croate" lang="hr" hreflang="hr" data-title="Relativna molekulska masa" data-language-autonym="Hrvatski" data-language-local-name="croate" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Molekulat%C3%B6meg" title="Molekulatömeg – hongrois" lang="hu" hreflang="hu" data-title="Molekulatömeg" data-language-autonym="Magyar" data-language-local-name="hongrois" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%84%D5%B8%D5%AC%D5%A5%D5%AF%D5%B8%D6%82%D5%AC%D5%A1%D5%B5%D5%AB%D5%B6_%D5%A6%D5%A1%D5%B6%D5%A3%D5%BE%D5%A1%D5%AE" title="Մոլեկուլային զանգված – arménien" lang="hy" hreflang="hy" data-title="Մոլեկուլային զանգված" data-language-autonym="Հայերեն" data-language-local-name="arménien" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Massa_molekul_relatif" title="Massa molekul relatif – indonésien" lang="id" hreflang="id" data-title="Massa molekul relatif" data-language-autonym="Bahasa Indonesia" data-language-local-name="indonésien" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Sameindamassi" title="Sameindamassi – islandais" lang="is" hreflang="is" data-title="Sameindamassi" data-language-autonym="Íslenska" data-language-local-name="islandais" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Massa_molecolare" title="Massa molecolare – italien" lang="it" hreflang="it" data-title="Massa molecolare" data-language-autonym="Italiano" data-language-local-name="italien" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E5%88%86%E5%AD%90%E9%87%8F" title="分子量 – japonais" lang="ja" hreflang="ja" data-title="分子量" data-language-autonym="日本語" data-language-local-name="japonais" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%9B%E1%83%9D%E1%83%9A%E1%83%94%E1%83%99%E1%83%A3%E1%83%9A%E1%83%A3%E1%83%A0%E1%83%98_%E1%83%9B%E1%83%90%E1%83%A1%E1%83%90" title="მოლეკულური მასა – géorgien" lang="ka" hreflang="ka" data-title="მოლეკულური მასა" data-language-autonym="ქართული" data-language-local-name="géorgien" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-kab mw-list-item"><a href="https://kab.wikipedia.org/wiki/Takura_tacubrant" title="Takura tacubrant – kabyle" lang="kab" hreflang="kab" data-title="Takura tacubrant" data-language-autonym="Taqbaylit" data-language-local-name="kabyle" class="interlanguage-link-target"><span>Taqbaylit</span></a></li><li class="interlanguage-link interwiki-kn mw-list-item"><a href="https://kn.wikipedia.org/wiki/%E0%B2%85%E0%B2%A3%E0%B3%81%E0%B2%A4%E0%B3%82%E0%B2%95" title="ಅಣುತೂಕ – kannada" lang="kn" hreflang="kn" data-title="ಅಣುತೂಕ" data-language-autonym="ಕನ್ನಡ" data-language-local-name="kannada" class="interlanguage-link-target"><span>ಕನ್ನಡ</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EB%B6%84%EC%9E%90%EB%9F%89" title="분자량 – coréen" lang="ko" hreflang="ko" data-title="분자량" data-language-autonym="한국어" data-language-local-name="coréen" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-ky mw-list-item"><a href="https://ky.wikipedia.org/wiki/%D0%9C%D0%BE%D0%BB%D0%B5%D0%BA%D1%83%D0%BB%D0%B0%D0%BB%D1%8B%D0%BA_%D0%BC%D0%B0%D1%81%D1%81%D0%B0" title="Молекулалык масса – kirghize" lang="ky" hreflang="ky" data-title="Молекулалык масса" data-language-autonym="Кыргызча" data-language-local-name="kirghize" class="interlanguage-link-target"><span>Кыргызча</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/Massa_muleculara" title="Massa muleculara – lombard" lang="lmo" hreflang="lmo" data-title="Massa muleculara" data-language-autonym="Lombard" data-language-local-name="lombard" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Molekulin%C4%97_mas%C4%97" title="Molekulinė masė – lituanien" lang="lt" hreflang="lt" data-title="Molekulinė masė" data-language-autonym="Lietuvių" data-language-local-name="lituanien" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Molekulu_masa" title="Molekulu masa – letton" lang="lv" hreflang="lv" data-title="Molekulu masa" data-language-autonym="Latviešu" data-language-local-name="letton" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%9C%D0%BE%D0%BB%D0%B5%D0%BA%D1%83%D0%BB%D1%81%D0%BA%D0%B0_%D0%BC%D0%B0%D1%81%D0%B0" title="Молекулска маса – macédonien" lang="mk" hreflang="mk" data-title="Молекулска маса" data-language-autonym="Македонски" data-language-local-name="macédonien" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-mr mw-list-item"><a href="https://mr.wikipedia.org/wiki/%E0%A4%B0%E0%A5%87%E0%A4%A3%E0%A5%81%E0%A4%AD%E0%A4%BE%E0%A4%B0" title="रेणुभार – marathi" lang="mr" hreflang="mr" data-title="रेणुभार" data-language-autonym="मराठी" data-language-local-name="marathi" class="interlanguage-link-target"><span>मराठी</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Jisim_molekul" title="Jisim molekul – malais" lang="ms" hreflang="ms" data-title="Jisim molekul" data-language-autonym="Bahasa Melayu" data-language-local-name="malais" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Moleculaire_massa" title="Moleculaire massa – néerlandais" lang="nl" hreflang="nl" data-title="Moleculaire massa" data-language-autonym="Nederlands" data-language-local-name="néerlandais" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Molekylmasse" title="Molekylmasse – norvégien nynorsk" lang="nn" hreflang="nn" data-title="Molekylmasse" data-language-autonym="Norsk nynorsk" data-language-local-name="norvégien nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Massa_moleculara" title="Massa moleculara – occitan" lang="oc" hreflang="oc" data-title="Massa moleculara" data-language-autonym="Occitan" data-language-local-name="occitan" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-pa mw-list-item"><a href="https://pa.wikipedia.org/wiki/%E0%A8%85%E0%A8%A3%E0%A8%B5%E0%A9%80_%E0%A8%AD%E0%A8%BE%E0%A8%B0" title="ਅਣਵੀ ਭਾਰ – pendjabi" lang="pa" hreflang="pa" data-title="ਅਣਵੀ ਭਾਰ" data-language-autonym="ਪੰਜਾਬੀ" data-language-local-name="pendjabi" class="interlanguage-link-target"><span>ਪੰਜਾਬੀ</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Masa_cz%C4%85steczkowa" title="Masa cząsteczkowa – polonais" lang="pl" hreflang="pl" data-title="Masa cząsteczkowa" data-language-autonym="Polski" data-language-local-name="polonais" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Massa_molecular" title="Massa molecular – portugais" lang="pt" hreflang="pt" data-title="Massa molecular" data-language-autonym="Português" data-language-local-name="portugais" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Mas%C4%83_molecular%C4%83" title="Masă moleculară – roumain" lang="ro" hreflang="ro" data-title="Masă moleculară" data-language-autonym="Română" data-language-local-name="roumain" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9C%D0%BE%D0%BB%D0%B5%D0%BA%D1%83%D0%BB%D1%8F%D1%80%D0%BD%D0%B0%D1%8F_%D0%BC%D0%B0%D1%81%D1%81%D0%B0" title="Молекулярная масса – russe" lang="ru" hreflang="ru" data-title="Молекулярная масса" data-language-autonym="Русский" data-language-local-name="russe" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Molekulska_masa" title="Molekulska masa – serbo-croate" lang="sh" hreflang="sh" data-title="Molekulska masa" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="serbo-croate" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Molecular_mass" title="Molecular mass – Simple English" lang="en-simple" hreflang="en-simple" data-title="Molecular mass" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Molekulov%C3%A1_hmotnos%C5%A5" title="Molekulová hmotnosť – slovaque" lang="sk" hreflang="sk" data-title="Molekulová hmotnosť" data-language-autonym="Slovenčina" data-language-local-name="slovaque" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Molekulska_masa" title="Molekulska masa – slovène" lang="sl" hreflang="sl" data-title="Molekulska masa" data-language-autonym="Slovenščina" data-language-local-name="slovène" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%9C%D0%BE%D0%BB%D0%B5%D0%BA%D1%83%D0%BB%D1%81%D0%BA%D0%B0_%D0%BC%D0%B0%D1%81%D0%B0" title="Молекулска маса – serbe" lang="sr" hreflang="sr" data-title="Молекулска маса" data-language-autonym="Српски / srpski" data-language-local-name="serbe" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-su mw-list-item"><a href="https://su.wikipedia.org/wiki/Beurat_molekul" title="Beurat molekul – soundanais" lang="su" hreflang="su" data-title="Beurat molekul" data-language-autonym="Sunda" data-language-local-name="soundanais" class="interlanguage-link-target"><span>Sunda</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Molekylmassa" title="Molekylmassa – suédois" lang="sv" hreflang="sv" data-title="Molekylmassa" data-language-autonym="Svenska" data-language-local-name="suédois" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%A1%E0%B8%A7%E0%B8%A5%E0%B9%82%E0%B8%A1%E0%B9%80%E0%B8%A5%E0%B8%81%E0%B8%B8%E0%B8%A5" title="มวลโมเลกุล – thaï" lang="th" hreflang="th" data-title="มวลโมเลกุล" data-language-autonym="ไทย" data-language-local-name="thaï" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Molek%C3%BCl_k%C3%BCtlesi" title="Molekül kütlesi – turc" lang="tr" hreflang="tr" data-title="Molekül kütlesi" data-language-autonym="Türkçe" data-language-local-name="turc" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9C%D0%BE%D0%BB%D0%B5%D0%BA%D1%83%D0%BB%D1%8F%D1%80%D0%BD%D0%B0_%D0%BC%D0%B0%D1%81%D0%B0" title="Молекулярна маса – ukrainien" lang="uk" hreflang="uk" data-title="Молекулярна маса" data-language-autonym="Українська" data-language-local-name="ukrainien" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D8%B3%D8%A7%D9%84%D9%85%DB%8C_%DA%A9%D9%85%DB%8C%D8%AA" title="سالمی کمیت – ourdou" lang="ur" hreflang="ur" data-title="سالمی کمیت" data-language-autonym="اردو" data-language-local-name="ourdou" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link 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class="mw-indicators"> </div> <div id="siteSub" class="noprint">Un article de Wikipédia, l'encyclopédie libre.</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="fr" dir="ltr"><div class="bandeau-container metadata homonymie hatnote"><div class="bandeau-cell bandeau-icone" style="display:table-cell;padding-right:0.5em"><span class="noviewer" typeof="mw:File"><a href="/wiki/Aide:Homonymie" title="Aide:Homonymie"><img alt="Page d’aide sur l’homonymie" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Logo_disambig.svg/20px-Logo_disambig.svg.png" decoding="async" width="20" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Logo_disambig.svg/30px-Logo_disambig.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Logo_disambig.svg/40px-Logo_disambig.svg.png 2x" data-file-width="512" data-file-height="375" /></a></span></div><div class="bandeau-cell" style="display:table-cell;padding-right:0.5em"> <p>Pour les articles homonymes, voir <a href="/wiki/Masse_(homonymie)" class="mw-disambig" title="Masse (homonymie)">Masse (homonymie)</a>. </p> </div></div> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Masse_moléculaire_(absolue)"><span id="Masse_mol.C3.A9culaire_.28absolue.29"></span>Masse moléculaire (absolue)</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=1" title="Modifier la section : Masse moléculaire (absolue)" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=1" title="Modifier le code source de la section : Masse moléculaire (absolue)"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>La <b>masse moléculaire</b> (absolue) est la masse d'une molécule, exprimée en <a href="/wiki/Unit%C3%A9_de_masse_atomique_unifi%C3%A9e" title="Unité de masse atomique unifiée">unité de masse atomique</a> : « uma » (équivalente à un douzième, soit 1/12, de la masse d'un <a href="/wiki/Atome" title="Atome">atome</a> de <span class="nowrap"><a href="/wiki/Carbone_12" title="Carbone 12">carbone 12</a></span>). </p><p>Elle peut être obtenue par l'addition de la <a href="/wiki/Masse_atomique" title="Masse atomique">masse atomique</a> (absolue, mesurée en uma) de chaque atome de la molécule multipliée par leur indice numérique dans la <a href="/wiki/Formule_brute" title="Formule brute">formule brute</a> ou mesurée expérimentalement par <a href="/wiki/Spectrom%C3%A9trie_de_masse" title="Spectrométrie de masse">spectrométrie de masse</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Masse_moléculaire_(relative)"><span id="Masse_mol.C3.A9culaire_.28relative.29"></span>Masse moléculaire (relative)</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=2" title="Modifier la section : Masse moléculaire (relative)" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=2" title="Modifier le code source de la section : Masse moléculaire (relative)"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>La <b>masse moléculaire relative</b> est le rapport entre la masse moléculaire absolue (en uma) et l'<a href="/wiki/Unit%C3%A9_de_masse_atomique_unifi%C3%A9e" title="Unité de masse atomique unifiée">unité de masse atomique</a> « uma ». Elle est numériquement égale à la masse moléculaire absolue, mais sans unité du fait de la division par 1 <abbr class="abbr" title="unité de masse atomique">uma</abbr>. Il s'agit du nombre d'uma compris dans la masse de la molécule. </p><p>Elle peut être obtenue par l'addition de la <a href="/wiki/Masse_atomique" title="Masse atomique">masse atomique</a> relative (nombre sans unité) de chaque atome de la molécule multipliée par leur indice numérique dans la <a href="/wiki/Formule_brute" title="Formule brute">formule brute</a>. </p><p>Pour les composés qui ne contiennent pas de molécules (composés <a href="/wiki/Ion" title="Ion">ioniques</a>, <a href="/wiki/Alliage" title="Alliage">alliages métalliques</a>, la quasi-totalité des <a href="/wiki/Min%C3%A9ral" title="Minéral">minéraux</a>), on parle de <b>masse formulaire</b> ou <b>masse de l'unité de formule</b>. </p> <div class="mw-heading mw-heading2"><h2 id="Masse_moléculaire_des_polymères"><span id="Masse_mol.C3.A9culaire_des_polym.C3.A8res"></span>Masse moléculaire des polymères</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=3" title="Modifier la section : Masse moléculaire des polymères" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=3" title="Modifier le code source de la section : Masse moléculaire des polymères"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="bandeau-container bandeau-section metadata bandeau-niveau-information"><div class="bandeau-cell bandeau-icone-css loupe">Article détaillé : <a href="/wiki/Grandeurs_caract%C3%A9ristiques_des_polym%C3%A8res" class="mw-redirect" title="Grandeurs caractéristiques des polymères">Grandeurs caractéristiques des polymères</a>.</div></div> <p>Un <a href="/wiki/Polym%C3%A8re" title="Polymère">polymère</a> étant constitué d'une distribution de chaînes de longueurs différentes, on doit parler de masse moléculaire moyenne : </p><p>Soit : </p> <dl><dd><i>x</i> le <a href="/wiki/Degr%C3%A9_de_polym%C3%A9risation" title="Degré de polymérisation">degré de polymérisation</a> ;</dd> <dd><i>n</i><sub><i>x</i></sub> le nombre de <a href="/wiki/Macromol%C3%A9cule" title="Macromolécule">macromolécules</a> de degré de polymérisation <i>x</i> ;</dd> <dd><i>M</i><sub><i>x</i></sub> la masse de telles macromolécules ;</dd> <dd><i>M</i><sub>0</sub> la masse d'un <a href="/wiki/Monom%C3%A8re" title="Monomère">monomère</a>,</dd></dl> <ul><li>on définit la masse moléculaire moyenne en nombre :</li></ul> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\bar {M}}_{n}={\frac {\sum n_{x}M_{x}}{\sum n_{x}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>M</mi> <mo stretchy="false">¯</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mo>∑</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> </msub> <msub> <mi>M</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> </msub> </mrow> <mrow> <mo>∑</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> </msub> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\bar {M}}_{n}={\frac {\sum n_{x}M_{x}}{\sum n_{x}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/11a39a548159e0f28795636e750388edf12cd16f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:16.43ex; height:6.509ex;" alt="{\displaystyle {\bar {M}}_{n}={\frac {\sum n_{x}M_{x}}{\sum n_{x}}}}"></span>.</dd></dl> <ul><li>De même, on définit la masse moléculaire moyenne en poids :</li></ul> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\bar {M}}_{w}={\frac {\sum n_{x}M_{x}^{2}}{\sum n_{x}M_{x}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>M</mi> <mo stretchy="false">¯</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>w</mi> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mo>∑</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> </msub> <msubsup> <mi>M</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msubsup> </mrow> <mrow> <mo>∑</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> </msub> <msub> <mi>M</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> </msub> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\bar {M}}_{w}={\frac {\sum n_{x}M_{x}^{2}}{\sum n_{x}M_{x}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/4a6db1f11b11ffd64377815b2d126d5847e1a797" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:16.747ex; height:6.676ex;" alt="{\displaystyle {\bar {M}}_{w}={\frac {\sum n_{x}M_{x}^{2}}{\sum n_{x}M_{x}}}}"></span>.</dd></dl> <dl><dd>N.B. : dans le cas de polymères isomoléculaires, ces deux masses sont identiques.</dd></dl> <ul><li>On définit également la moyenne de centrifugation (ou de sédimentation) :</li></ul> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\bar {M}}_{z}={\frac {\sum n_{x}M_{x}^{3}}{\sum n_{x}M_{x}^{2}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>M</mi> <mo stretchy="false">¯</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>z</mi> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mo>∑</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> </msub> <msubsup> <mi>M</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mn>3</mn> </mrow> </msubsup> </mrow> <mrow> <mo>∑</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> </msub> <msubsup> <mi>M</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msubsup> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\bar {M}}_{z}={\frac {\sum n_{x}M_{x}^{3}}{\sum n_{x}M_{x}^{2}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/96f05a5dbc9a05831730562c2b07d0d487c499f5" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.838ex; width:16.34ex; height:6.843ex;" alt="{\displaystyle {\bar {M}}_{z}={\frac {\sum n_{x}M_{x}^{3}}{\sum n_{x}M_{x}^{2}}}}"></span>.</dd></dl> <ul><li>On définit l'indice de polydispersité par :</li></ul> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle I={\frac {{\bar {M}}_{w}}{{\bar {M}}_{n}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>I</mi> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>M</mi> <mo stretchy="false">¯</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>w</mi> </mrow> </msub> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>M</mi> <mo stretchy="false">¯</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msub> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle I={\frac {{\bar {M}}_{w}}{{\bar {M}}_{n}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/87db2f74bc61bf5075c7c11206f93e04608a9f69" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:8.958ex; height:6.509ex;" alt="{\displaystyle I={\frac {{\bar {M}}_{w}}{{\bar {M}}_{n}}}}"></span>.</dd></dl> <p>Les propriétés des polymères dépendent grandement de ces deux masses moyennes :<br /> Des propriétés mécaniques élevées nécessitent une <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\bar {M}}_{n}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>M</mi> <mo stretchy="false">¯</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\bar {M}}_{n}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/cb34be88d91df81545ba771c1886c98df4b64765" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.661ex; height:2.843ex;" alt="{\displaystyle {\bar {M}}_{n}}"></span> élevée tandis qu'une <a href="/wiki/Mise_en_forme_d%27un_mat%C3%A9riau#Matières_plastiques" title="Mise en forme d'un matériau">mise en œuvre</a> aisée demande une <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\bar {M}}_{w}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>M</mi> <mo stretchy="false">¯</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>w</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\bar {M}}_{w}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/7441e2d81105265ca542eb3b423852f36a9bd219" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.851ex; height:2.843ex;" alt="{\displaystyle {\bar {M}}_{w}}"></span> modérée. </p><p>Ces masses peuvent être déterminées par <a href="/wiki/Chromatographie_d%27exclusion_st%C3%A9rique" title="Chromatographie d'exclusion stérique">chromatographie d'exclusion stérique (SEC)</a> aussi appelée <a href="/wiki/Chromatographie_sur_gel_perm%C3%A9able" class="mw-redirect" title="Chromatographie sur gel perméable">chromatographie sur gel perméable (GPC)</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Masse_moléculaire_des_protéines"><span id="Masse_mol.C3.A9culaire_des_prot.C3.A9ines"></span>Masse moléculaire des protéines</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=4" title="Modifier la section : Masse moléculaire des protéines" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=4" title="Modifier le code source de la section : Masse moléculaire des protéines"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>La masse moléculaire des <a href="/wiki/Prot%C3%A9ine" title="Protéine">protéines</a> peut être déterminée selon l'une des méthodes suivantes<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite_crochet">[</span>1<span class="cite_crochet">]</span></a></sup> : </p> <ul><li>méthodes chimiques : dosage d'un élément n'existant qu'à un petit nombre d'exemplaires dans la protéine ;</li> <li>méthodes physiques : <ul><li>mesure de la <a href="/wiki/Pression_osmotique" class="mw-redirect" title="Pression osmotique">pression osmotique</a>,</li> <li><a href="/wiki/%C3%89lectrophor%C3%A8se_sur_gel_de_polyacrylamide_en_pr%C3%A9sence_de_dod%C3%A9cylsulfate_de_sodium" title="Électrophorèse sur gel de polyacrylamide en présence de dodécylsulfate de sodium">électrophorèse sur gel de polyacrylamide en présence de dodécylsulfate de sodium</a>,</li> <li>chromatographie par filtration de gel, une méthode de <a href="/wiki/Chromatographie_d%E2%80%99exclusion_st%C3%A9rique" class="mw-redirect" title="Chromatographie d’exclusion stérique">chromatographie d’exclusion stérique</a>,</li> <li><a href="/wiki/Ultracentrifugation" title="Ultracentrifugation">ultracentrifugation</a>.</li></ul></li></ul> <div class="mw-heading mw-heading2"><h2 id="Détermination"><span id="D.C3.A9termination"></span>Détermination</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=5" title="Modifier la section : Détermination" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=5" title="Modifier le code source de la section : Détermination"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Spectrométrie_de_masse"><span id="Spectrom.C3.A9trie_de_masse"></span>Spectrométrie de masse</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=6" title="Modifier la section : Spectrométrie de masse" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=6" title="Modifier le code source de la section : Spectrométrie de masse"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>En <a href="/wiki/Spectrom%C3%A9trie_de_masse" title="Spectrométrie de masse">spectrométrie de masse</a>, la masse d'une <a href="/wiki/Petite_mol%C3%A9cule" title="Petite molécule">petite molécule</a> est généralement rapportée comme la <a href="/wiki/Masse_mono-isotopique" title="Masse mono-isotopique">masse mono-isotopique</a>, c'est-à-dire la masse de la molécule contenant uniquement l'isotope le plus commun de chaque élément chimique. Les masses utilisées pour calculer la masse mono-isotopique se trouvent sur la <a href="/wiki/Table_des_isotopes" title="Table des isotopes">table des isotopes</a>, et non sur le <a href="/wiki/Tableau_p%C3%A9riodique_des_%C3%A9l%C3%A9ments" title="Tableau périodique des éléments">tableau périodique des éléments</a> classique. La masse moléculaire moyenne est souvent utilisée pour de plus grandes molécules puisque celles avec de nombreux atomes sont peu susceptibles d'être composées exclusivement de l'isotope le plus abondant de chaque élément. Une masse moléculaire moyenne théorique peut être calculée en utilisant les <a href="/wiki/Masse_atomique" title="Masse atomique">masses atomiques relatives</a> figurant sur le tableau périodique typique, étant donné qu'elle est susceptible d'être la répartition statistique des atomes représentant les isotopes dans la molécule. Cela peut toutefois être différent de la vraie masse moléculaire moyenne de l'échantillon due à des variations naturelles (ou artificielles) dans la répartition isotopique. </p> <div class="mw-heading mw-heading3"><h3 id="Méthodes_hydrodynamiques"><span id="M.C3.A9thodes_hydrodynamiques"></span>Méthodes hydrodynamiques</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=7" title="Modifier la section : Méthodes hydrodynamiques" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=7" title="Modifier le code source de la section : Méthodes hydrodynamiques"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>En première approximation, la base de la détermination du poids moléculaire selon l'<a href="/wiki/Viscosit%C3%A9_d%27une_solution_polym%C3%A8re#Détermination_de_la_masse_molaire_moyenne_viscosimétrique" title="Viscosité d'une solution polymère">équation de Mark-Houwink</a> est le fait que la <a href="/wiki/Viscosit%C3%A9_d%27une_solution_polym%C3%A8re" title="Viscosité d'une solution polymère">viscosité</a> de la <a href="/wiki/Solution_(chimie)" title="Solution (chimie)">solution</a> (ou <a href="/wiki/Suspension_(chimie)" title="Suspension (chimie)">suspension</a>) des macromolécules dépend de la proportion volumique des particules dispersées dans un solvant particulier. Plus précisément, la taille hydrodynamique est liée à la masse moléculaire qui dépend d'un facteur de conversion, en décrivant la forme d'une molécule particulière. Cela permet au poids moléculaire d'être décrit grâce à des techniques sensibles aux effets hydrodynamiques, comme la <a href="/wiki/Diffusion_dynamique_de_la_lumi%C3%A8re" title="Diffusion dynamique de la lumière">diffusion dynamique de la lumière</a> (DLS), la <a href="/wiki/Chromatographie_d%27exclusion_st%C3%A9rique" title="Chromatographie d'exclusion stérique">chromatographie d'exclusion stérique</a> (SEC) ou encore la <a href="/wiki/Viscosim%C3%A8tre" title="Viscosimètre">viscosimétrie</a>. L'apparente taille hydrodynamique peut alors être utilisée pour calculer le poids moléculaire en utilisant une série de normes spécifiques à la macromolécule. Comme cela nécessite un étalonnage, cette méthode est souvent décrite comme une méthode moléculaire « relative » de la détermination du poids. </p> <div class="mw-heading mw-heading3"><h3 id="Diffusion_statique_de_la_lumière"><span id="Diffusion_statique_de_la_lumi.C3.A8re"></span>Diffusion statique de la lumière</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=8" title="Modifier la section : Diffusion statique de la lumière" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=8" title="Modifier le code source de la section : Diffusion statique de la lumière"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Il est également possible de déterminer directement la masse moléculaire absolue de diffusion de la lumière, traditionnellement en utilisant la <a href="/wiki/Diffusion_statique_de_la_lumi%C3%A8re#Représentation_de_Zimm" title="Diffusion statique de la lumière">méthode de Zimm</a>. Ceci peut être réalisé soit par l'intermédiaire classique de détecteurs de <a href="/wiki/Diffusion_statique_de_la_lumi%C3%A8re" title="Diffusion statique de la lumière">diffusion de lumière statique</a><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite_crochet">[</span>2<span class="cite_crochet">]</span></a></sup> ou par l'intermédiaire d'une <a href="/wiki/Diffusion_statique_de_la_lumi%C3%A8re#Diffusion_de_la_lumière_sous_multiples_angles" title="Diffusion statique de la lumière">diffusion de la lumière sous multiples angles</a>. Les poids moléculaires déterminés par ces méthodes ne nécessitent pas de calibration, d'où le terme « absolue ». La seule mesure externe requise est l'<a href="/wiki/Diffusion_statique_de_la_lumi%C3%A8re#Théorie" title="Diffusion statique de la lumière">incrément d'indice de réfraction</a>, qui décrit le changement d'indice de réfraction avec la concentration. </p> <div class="mw-heading mw-heading2"><h2 id="Articles_connexes">Articles connexes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=9" title="Modifier la section : Articles connexes" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=9" title="Modifier le code source de la section : Articles connexes"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Masse_atomique" title="Masse atomique">Masse atomique</a></li> <li><a href="/wiki/Masse_molaire" title="Masse molaire">Masse molaire</a></li></ul> <table class="wikitable"> <caption>Synoptique des grandeurs de masse moléculaire </caption> <tbody><tr> <th>Grandeur</th> <th>Définition</th> <th>Unité</th> <th>Remarque </th></tr> <tr> <td><a href="/wiki/Nombre_de_masse" title="Nombre de masse">Nombre de masse</a></td> <td>Le nombre de nucléons d'un atome.</td> <td>Entier sans dimension.</td> <td>La différence entre le nombre de masse et la masse atomique relative de l'atome vient de la légère différence de masse entre le proton et le neutron, ainsi que de l'énergie de <a href="/wiki/Liaison_nucl%C3%A9aire" title="Liaison nucléaire">liaison nucléaire</a>, et est typiquement inférieure au pour cent. </td></tr> <tr> <td><a href="/wiki/Masse_atomique" title="Masse atomique">Masse atomique ou moléculaire</a></td> <td>La masse d'un atome ou d'une molécule.</td> <td>(<a href="/wiki/Kilogramme" title="Kilogramme">kilogramme</a>) <a href="/wiki/Unit%C3%A9_de_masse_atomique" class="mw-redirect" title="Unité de masse atomique">uma</a></td> <td>Exprimée en <a href="/wiki/Unit%C3%A9_de_masse_atomique" class="mw-redirect" title="Unité de masse atomique">unité de masse atomique</a>, la masse atomique ou moléculaire indique la masse individuelle d'un atome ou d'une molécule. </td></tr> <tr> <td>Masse atomique ou moléculaire relative</td> <td>Rapport entre la masse (exprimée en uma) d'un atome ou d'une molécule et l'unité de masse atomique.</td> <td>Nombre sans dimension.</td> <td>La masse moléculaire relative correspond au total des nombres de masse des atomes de la molécule. Pour un atome individuel, la masse atomique relative est peu différente de son nombre de masse. </td></tr> <tr> <td><a href="/wiki/Masse_molaire" title="Masse molaire">Masse molaire</a></td> <td>La masse d'une mole d'une molécule (ou d'un atome).</td> <td>(kg/mol) g/mol</td> <td>Exprimée en <a href="/wiki/Gramme" title="Gramme">gramme</a> par <a href="/wiki/Mole_(unit%C3%A9)" title="Mole (unité)">mole</a>, la mesure de la masse molaire est égale à la masse moléculaire. </td></tr> <tr> <td><a href="/wiki/Unit%C3%A9_de_masse_atomique" class="mw-redirect" title="Unité de masse atomique">Unité de masse atomique</a> (uma ou u)</td> <td>Le douzième de la masse d'un atome de <span class="nowrap"><a href="/wiki/Carbone_12" title="Carbone 12">carbone 12</a></span>.</td> <td>(<a href="/wiki/Kilogramme" title="Kilogramme">kilogramme</a>)</td> <td>Elle vaut 1,66 × 10<sup>−27</sup> <abbr class="abbr" title="kilogramme">kg</abbr>, sensiblement la masse d'un proton (1,672 × 10<sup>−27</sup> <abbr class="abbr" title="kilogramme">kg</abbr>) ou d'un neutron (1,675 × 10<sup>−27</sup> <abbr class="abbr" title="kilogramme">kg</abbr>), la différence correspond à l'énergie de <a href="/wiki/Liaison_nucl%C3%A9aire" title="Liaison nucléaire">liaison nucléaire</a> du carbone. L'unité de masse atomique est également appelée « <a href="/wiki/Unit%C3%A9_de_masse_atomique_unifi%C3%A9e#En_biochimie" title="Unité de masse atomique unifiée">dalton</a> » (Da), en particulier en biologie. </td></tr> <tr> <td><a href="/wiki/Mole_(unit%C3%A9)" title="Mole (unité)">Mole</a> (mol)</td> <td><a href="/wiki/Quantit%C3%A9_de_mati%C3%A8re" title="Quantité de matière">Quantité de matière</a> d'un système contenant autant d'entités élémentaires qu'il y a d'atomes dans douze grammes de <span class="nowrap">carbone 12</span>.</td> <td><a href="/wiki/Mole_(unit%C3%A9)" title="Mole (unité)">mole</a> (mol)</td> <td>Le nombre d'entités est le <a href="/wiki/Nombre_d%27Avogadro" title="Nombre d'Avogadro">nombre d'Avogadro</a>, 6,022 × 10<sup>23</sup> <abbr class="abbr" title="par mole">mol<sup>−1</sup></abbr>. </td></tr></tbody></table> <div class="mw-heading mw-heading2"><h2 id="Références"><span id="R.C3.A9f.C3.A9rences"></span>Références</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&veaction=edit&section=10" title="Modifier la section : Références" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Masse_mol%C3%A9culaire&action=edit&section=10" title="Modifier le code source de la section : Références"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><a href="#cite_ref-1">↑</a> </span><span class="reference-text">Alain Lavoinne (auteur), Soumeya Bekri (auteur), Pierre Kamoun (préface), <i>Aide-mémoire de biochimie et biologie moléculaire</i>, Médecine Sciences - Flammarion, <abbr class="abbr" title="Sixième">6<sup>e</sup></abbr> <abbr class="abbr" title="édition">éd.</abbr>, 2008.</span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><a href="#cite_ref-2">↑</a> </span><span class="reference-text"><a rel="nofollow" class="external text" href="http://www.malvern.com/fr/products/technology/static-light-scattering/">« Diffusion statique de la lumière (SLS) – Mesure de la masse molaire absolue par LALS, RALS ou MALS »</a>, sur <i>malvern.com</i>.</span> </li> </ol></div> <ul id="bandeau-portail" class="bandeau-portail"><li><span class="bandeau-portail-element"><span class="bandeau-portail-icone"><span class="noviewer" typeof="mw:File"><a href="/wiki/Portail:Chimie" title="Portail de la chimie"><img alt="icône décorative" src="//upload.wikimedia.org/wikipedia/commons/thumb/5/59/Nuvola_apps_edu_science.svg/24px-Nuvola_apps_edu_science.svg.png" decoding="async" width="24" height="24" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/59/Nuvola_apps_edu_science.svg/36px-Nuvola_apps_edu_science.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/59/Nuvola_apps_edu_science.svg/48px-Nuvola_apps_edu_science.svg.png 2x" data-file-width="128" data-file-height="128" /></a></span></span> <span class="bandeau-portail-texte"><a href="/wiki/Portail:Chimie" title="Portail:Chimie">Portail de la chimie</a></span> </span></li> </ul>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; 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