{"id":5853,"date":"2026-10-15T06:56:28","date_gmt":"2026-10-15T03:56:28","guid":{"rendered":"https:\/\/wpcalc.com\/fr\/chimie\/calculateur-loi-kohlrausch\/"},"modified":"2026-10-15T06:56:28","modified_gmt":"2026-10-15T03:56:28","slug":"calculateur-loi-kohlrausch","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/fr\/chimie\/calculateur-loi-kohlrausch\/","title":{"rendered":"Calculateur de la loi de Kohlrausch"},"content":{"rendered":"<section class=\"not-prose calculator-box\" aria-labelledby=\"calculator-title\"><div class=\"flex items-baseline sm:items-center justify-between gap-2 sm:gap-3\"><div class=\"flex flex-col sm:flex-row sm:items-center gap-2\"><span class=\"icon icon-calculator text-primary-700! text-base! dark:text-primary-300!\" aria-hidden=\"true\"><\/span><h2 id=\"calculator-title\" class=\"text-lg font-display font-bold\">Pr\u00e9dire la conductivit\u00e9 molaire limite d&#039;un \u00e9lectrolyte \u00e0 partir de ses ions<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"5853\" data-favorite-title=\"Loi de Kohlrausch\" data-favorite-url=\"https:\/\/wpcalc.com\/fr\/chimie\/calculateur-loi-kohlrausch\/\" data-favorite-excerpt=\"Calculez la conductivit\u00e9 molaire limite de tout \u00e9lectrolyte \u00e0 dilution infinie \u00e0 partir des conductivit\u00e9s ioniques et des coefficients st\u0153chiom\u00e9triques, gr\u00e2ce \u00e0 la loi de Kohlrausch sur la migration ind\u00e9pendante des ions.\" aria-label=\"Ajouter aux favoris\" data-favorite-icon=\"icon icon-scale\">\n    <span class=\"icon icon-shape-star-empty\" aria-hidden=\"true\"><\/span>\n  <\/button>\n  <div class=\"calcdash-favorite__tip\" aria-hidden=\"true\">\n   <span class=\"favorite-tooltip\" id=\"favorite-tooltip\"><\/span>\n  <\/div>\n  <span class=\"sr-only\" role=\"status\" id=\"favorite-status\"><\/span>\n<\/div><\/div><form action=\"https:\/\/wpcalc.com\/fr\/chimie\/calculateur-loi-kohlrausch\/\" method=\"POST\" class=\"calculator\" id=\"calculator-5853\" data-post=\"5853\"><fieldset class=\"fieldset-input is-2\"><legend class=\"sr-only\">Champs de saisie<\/legend><div class=\"is-single field\" id=\"input-1\"><span class=\"font-semibold\">Cation (ion positif)<\/span><\/div><div class=\"field\" id=\"input-2\"><label for=\"field-2\">Nom du cation<\/label><input type=\"text\" name=\"nom_du_cation\" id=\"field-2\" placeholder=\"ex. Na\u207a\" step=\"any\" value=\"Na\u207a\"\/><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-3\">Conductivit\u00e9 molaire limite (\u03bb\u00b0\u208a)<\/label><div class=\"term\">\u03bb\u00b0\u208a<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"conductivit_molaire_limite_\" id=\"field-3\" aria-describedby=\"calc-unit-3 calc-info-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"50.11\"\/><div class=\"unit\" id=\"calc-unit-3\">S\u00b7cm\u00b2\/mol<\/div><small id=\"calc-info-3\">Conductivit\u00e9 molaire ionique limite \u00e0 dilution infinie et \u00e0 25 \u00b0C (Na\u207a = 50,11, K\u207a = 73,5, Ca\u00b2\u207a = 119,0).<\/small><\/div><div class=\"field has-term\" id=\"input-4\"><label for=\"field-4\">Coefficient st\u0153chiom\u00e9trique (\u03bd\u208a)<\/label><div class=\"term\">\u03bd\u208a<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"coefficient_stchiomtrique_\" id=\"field-4\" aria-describedby=\"calc-info-4\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"1\" value=\"1\"\/><small id=\"calc-info-4\">Nombre de cations par unit\u00e9 de formule, par ex. 1 dans NaCl, 2 dans Ca(OH)\u2082.<\/small><\/div><div class=\"field is-checkbox is-single\" id=\"input-5\"><input type=\"checkbox\" id=\"field-5\" value=\"1\"\/><label for=\"field-5\">Ajouter un deuxi\u00e8me cation<\/label><\/div><div class=\"field\" id=\"input-6\" hidden><label for=\"field-6\">Nom du deuxi\u00e8me cation<\/label><input type=\"text\" name=\"nom_du_deuxime_cation\" id=\"field-6\" placeholder=\"ex. Ca\u00b2\u207a\" step=\"any\" value=\"Ca\u00b2\u207a\"\/><\/div><div class=\"field has-term\" id=\"input-7\" hidden><label for=\"field-7\">Conductivit\u00e9 molaire limite (\u03bb\u00b0\u208a\u2082)<\/label><div class=\"term\">\u03bb\u00b0\u208a\u2082<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"conductivit_molaire_limite_\" id=\"field-7\" aria-describedby=\"calc-unit-7\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"119\"\/><div class=\"unit\" id=\"calc-unit-7\">S\u00b7cm\u00b2\/mol<\/div><\/div><div class=\"field has-term\" id=\"input-8\" hidden><label for=\"field-8\">Coefficient st\u0153chiom\u00e9trique (\u03bd\u208a\u2082)<\/label><div class=\"term\">\u03bd\u208a\u2082<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"coefficient_stchiomtrique_\" id=\"field-8\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"1\" value=\"1\"\/><\/div><div class=\"is-single field\" id=\"input-9\"><span class=\"font-semibold\">Anion (ion n\u00e9gatif)<\/span><\/div><div class=\"field\" id=\"input-10\"><label for=\"field-10\">Nom de l&#039;anion<\/label><input type=\"text\" name=\"nom_de_lanion\" id=\"field-10\" placeholder=\"ex. Cl\u207b\" step=\"any\" value=\"Cl\u207b\"\/><\/div><div class=\"field has-term\" id=\"input-11\"><label for=\"field-11\">Conductivit\u00e9 molaire limite (\u03bb\u00b0\u208b)<\/label><div class=\"term\">\u03bb\u00b0\u208b<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"conductivit_molaire_limite_\" id=\"field-11\" aria-describedby=\"calc-unit-11 calc-info-11\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"76.35\"\/><div class=\"unit\" id=\"calc-unit-11\">S\u00b7cm\u00b2\/mol<\/div><small id=\"calc-info-11\">Conductivit\u00e9 molaire ionique limite \u00e0 dilution infinie et \u00e0 25 \u00b0C (Cl\u207b = 76,35, OH\u207b = 198,3, SO\u2084\u00b2\u207b = 160,0).<\/small><\/div><div class=\"field has-term\" id=\"input-12\"><label for=\"field-12\">Coefficient st\u0153chiom\u00e9trique (\u03bd\u208b)<\/label><div class=\"term\">\u03bd\u208b<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"coefficient_stchiomtrique_\" id=\"field-12\" aria-describedby=\"calc-info-12\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"1\" value=\"1\"\/><small id=\"calc-info-12\">Nombre d&#039;anions par unit\u00e9 de formule, par ex. 2 dans CaCl\u2082 ou Na\u2082SO\u2084.<\/small><\/div><div class=\"field is-checkbox is-single\" id=\"input-13\"><input type=\"checkbox\" id=\"field-13\" value=\"1\"\/><label for=\"field-13\">Ajouter un deuxi\u00e8me anion<\/label><\/div><div class=\"field\" id=\"input-14\" hidden><label for=\"field-14\">Nom du deuxi\u00e8me anion<\/label><input type=\"text\" name=\"nom_du_deuxime_anion\" id=\"field-14\" placeholder=\"ex. SO\u2084\u00b2\u207b\" step=\"any\" value=\"SO\u2084\u00b2\u207b\"\/><\/div><div class=\"field has-term\" id=\"input-15\" hidden><label for=\"field-15\">Conductivit\u00e9 molaire limite (\u03bb\u00b0\u208b\u2082)<\/label><div class=\"term\">\u03bb\u00b0\u208b\u2082<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"conductivit_molaire_limite_\" id=\"field-15\" aria-describedby=\"calc-unit-15\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"160\"\/><div class=\"unit\" id=\"calc-unit-15\">S\u00b7cm\u00b2\/mol<\/div><\/div><div class=\"field has-term\" id=\"input-16\" hidden><label for=\"field-16\">Coefficient st\u0153chiom\u00e9trique (\u03bd\u208b\u2082)<\/label><div class=\"term\">\u03bd\u208b\u2082<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"coefficient_stchiomtrique_\" id=\"field-16\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"1\" value=\"1\"\/><\/div><div class=\"field is-single\" id=\"input-17\"><label for=\"field-17\">Unit\u00e9 du r\u00e9sultat<\/label><div class=\"grid grid-cols-1\"><select id=\"field-17\" name=\"unit_du_rsultat\"><option value=\"scm2\" selected>S\u00b7cm\u00b2\/mol (usuel dans les tables)<\/option><option value=\"m2\">S\u00b7m\u00b2\/mol (SI)<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Recalculer\" id=\"calculate-button\" data-post=\"5853\">Calculer<\/button><button type=\"reset\">R\u00e9initialiser<\/button><\/div><div class=\"field is-checkbox hidden!\" id=\"field-auto-calc\"><input type=\"checkbox\" id=\"auto-calc\"><label for=\"auto-calc\">Calculer automatiquement<\/label><small>Si activ\u00e9, le r\u00e9sultat se met \u00e0 jour automatiquement d\u00e8s que vous modifiez une valeur.<\/small><\/div><div class=\"fieldset-result is-hidden\" aria-labelledby=\"result-title\" aria-live=\"polite\" role=\"region\"> <h3 class=\"result-title bg-gradient-to-r from-primary-50 to-gray-50 dark:from-primary-900 dark:to-gray-800\" id=\"result-title\"><span class=\"icon icon-s-pulse\" aria-hidden=\"true\"><\/span> R\u00e9sultats de la loi de Kohlrausch<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Conductivit\u00e9 molaire limite (\u039b\u00b0\u2098)<\/span><span class=\"result-term\">\u039b\u00b0\u2098<\/span><\/span><span class=\"field-value\" id=\"result-1\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copier le r\u00e9sultat\" aria-label=\"Copier le r\u00e9sultat\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-2\"><span class=\"field-title\"><span>Contributions des ions<\/span><\/span><span class=\"field-value\" id=\"result-2\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copier le r\u00e9sultat\" aria-label=\"Copier le r\u00e9sultat\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-3\"><span class=\"field-title\"><span>D\u00e9tails du calcul<\/span><\/span><span class=\"field-value\" id=\"result-3\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copier le r\u00e9sultat\" aria-label=\"Copier le r\u00e9sultat\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-4\"><span class=\"field-title\"><span>\u00c0 propos de la loi de Kohlrausch sur la migration ind\u00e9pendante des ions<\/span><\/span><span class=\"field-value\" id=\"result-4\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copier le r\u00e9sultat\" aria-label=\"Copier le r\u00e9sultat\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><\/div><div class=\"result-actions\"><button type=\"button\" class=\"copy-link\"><svg viewBox=\"0 0 20 20\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M12.232 4.232a2.5 2.5 0 0 1 3.536 3.536l-1.225 1.224a.75.75 0 0 0 1.061 1.06l1.224-1.224a4 4 0 0 0-5.656-5.656l-3 3a4 4 0 0 0 .225 5.865.75.75 0 0 0 .977-1.138 2.5 2.5 0 0 1-.142-3.667l3-3Z\"\/><path d=\"M11.603 7.963a.75.75 0 0 0-.977 1.138 2.5 2.5 0 0 1 .142 3.667l-3 3a2.5 2.5 0 0 1-3.536-3.536l1.225-1.224a.75.75 0 0 0-1.061-1.06l-1.224 1.224a4 4 0 1 0 5.656 5.656l3-3a4 4 0 0 0-.225-5.865Z\"\/><\/svg><span class=\"copy-link__text\">Copier le lien vers ce calcul<\/span><\/button><span class=\"sr-only\" role=\"status\" id=\"copy-link-status\"><\/span><\/div><\/div><a href=\"#respond\" class=\"hidden transition-opacity duration-300 opacity-0 w-50 text-sm justify-center items-center gap-2 px-4 py-2 rounded bg-gray-200 text-gray-700 hover:bg-gray-300\" id=\"leave-comment\"><span class=\"icon icon-comments\" aria-hidden=\"true\"><\/span>Laisser un commentaire<\/a><\/form><\/section><section id=\"calc-reactions\" class=\"not-prose hidden my-12 bg-gradient-to-r from-primary-50 to-gray-50 border border-indigo-100 rounded-xl px-6 py-4 shadow-sm\" data-post=\"5853\" aria-live=\"polite\" aria-labelledby=\"calc-reactions-title\"><p id=\"calc-reactions-title\" class=\"text-sm text-gray-500 text-center mb-2\">Que pensez-vous de ce r\u00e9sultat\u00a0?<\/p><div role=\"group\" aria-labelledby=\"calc-reactions-title\" class=\"grid grid-cols-3 sm:flex sm:flex-row sm:justify-around gap-4 sm:items-center sm:flex-wrap\"><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"like\"><span class=\"reaction-count\" data-reaction-count=\"like\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude00 <\/span><span class=\"reaction-description font-medium\">J\u2019aime <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"helpful\"><span class=\"reaction-count\" data-reaction-count=\"helpful\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\udca1 <\/span><span class=\"reaction-description font-medium\">Utile <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"confused\"><span class=\"reaction-count\" data-reaction-count=\"confused\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude15 <\/span><span class=\"reaction-description font-medium\">Confus <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"disappointed\"><span class=\"reaction-count\" data-reaction-count=\"disappointed\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude1e <\/span><span class=\"reaction-description font-medium\">D\u00e9\u00e7u <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"inaccurate\"><span class=\"reaction-count\" data-reaction-count=\"inaccurate\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\u274c <\/span><span class=\"reaction-description font-medium\">Inexact <\/span><\/button><\/div><div id=\"reaction-message\" class=\"hidden mt-8 rounded-md border border-primary-100 bg-white\/50 backdrop-blur-sm px-4 py-2 text-sm text-center shadow-sm\"><\/div><\/section><div class=\"calcdash-ad not-prose calcdash-ad--calc_result calcdash-ad--in-article\"><ins class=\"adsbygoogle\" style=\"display:block\" data-ad-client=\"ca-pub-1721569815777345\" data-ad-slot=\"6317458308\" data-ad-layout=\"in-article\" data-ad-format=\"fluid\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<style id=\"wpcoderpro-inline-1\">.formula-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section class=\"formula-box\" aria-labelledby=\"formula-title\">\r\n\t<div id=\"formula-title\" class=\"not-prose font-display mb-4\"><span class=\"icon icon-formula\" aria-hidden=\"true\"><\/span><h2>Formule de la loi de Kohlrausch<\/h2><\/div>\r\n\t<figure class=\"not-prose formula\">\r\n\t\t<figcaption class=\"formula-title\">Formule<\/figcaption>\r\n\t\t<div class=\"text-base text-gray-800\" id=\"formula\">\n\\[ \\Lambda^\\circ_m = \\nu_+ \\lambda^\\circ_+ + \\nu_- \\lambda^\\circ_- \\quad \\text{ou, de mani\u00e8re g\u00e9n\u00e9rale,} \\quad \\Lambda^\\circ_m = \\sum_i \\nu_i \\lambda^\\circ_i \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>O\u00f9&nbsp;:<\/strong><\/p>\n<ul>\n<li>\\(\\Lambda^\\circ_m\\) \u2014 conductivit\u00e9 molaire limite de l'\u00e9lectrolyte \u00e0 dilution infinie (S\u00b7cm\u00b2\/mol)<\/li>\n<li>\\(\\lambda^\\circ_i\\) \u2014 conductivit\u00e9 molaire limite (conductivit\u00e9 ionique) de l'ion \\(i\\) \u00e0 dilution infinie (S\u00b7cm\u00b2\/mol)<\/li>\n<li>\\(\\nu_i\\) \u2014 coefficient st\u0153chiom\u00e9trique de l'ion \\(i\\) dans l'unit\u00e9 formulaire (par exemple 2 pour Cl\u207b dans CaCl\u2082)<\/li>\n<\/ul>\n<p>Cette formule traduit la loi de Kohlrausch sur la migration ind\u00e9pendante des ions&nbsp;: \u00e0 dilution infinie, chaque ion contribue \u00e0 la conductivit\u00e9 totale ind\u00e9pendamment de tous les autres ; la conductivit\u00e9 molaire limite de l'\u00e9lectrolyte est donc simplement la somme des conductivit\u00e9s ioniques pond\u00e9r\u00e9es par leurs coefficients st\u0153chiom\u00e9triques.<\/p>\n<p>\r\n<\/section>\n<style id=\"wpcoderpro-inline-2\">.calculation-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section id=\"calculation\" class=\"calculation-box\" aria-labelledby=\"calculation-title\">\r\n\t<div id=\"calculation-title\" class=\"not-prose font-display\"><span class=\"icon icon-unordered-list\" aria-hidden=\"true\"><\/span><h2>Loi de Kohlrausch \u2013 Exemple de calcul<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Exemple&nbsp;:<\/strong> un \u00e9lectrolyte dont l'unit\u00e9 formulaire contient un ion Na\u207a, un ion Ca\u00b2\u207a, un ion Cl\u207b et un ion SO\u2084\u00b2\u207b. Les quatre ions ont un coefficient st\u0153chiom\u00e9trique de 1 et leurs conductivit\u00e9s molaires limites \u00e0 25 \u00b0C valent \u03bb\u00b0(Na\u207a) = 50,11, \u03bb\u00b0(Ca\u00b2\u207a) = 119,0, \u03bb\u00b0(Cl\u207b) = 76,35 et \u03bb\u00b0(SO\u2084\u00b2\u207b) = 160,0 S\u00b7cm\u00b2\/mol \u2014 ce sont exactement les valeurs par d\u00e9faut du calculateur.<\/p>\n<p>\\[ \\Lambda^\\circ_m = 1 \\times 50.11 + 1 \\times 119.0 + 1 \\times 76.35 + 1 \\times 160.0 = 405.46 \\ \\text{S\u00b7cm}^2\\!\/\\text{mol} \\]<\/p>\n<p><strong>R\u00e9sultat&nbsp;:<\/strong> \\(\\Lambda^\\circ_m = 405.46\\) S\u00b7cm\u00b2\/mol (soit 0,040546 S\u00b7m\u00b2\/mol).<\/p>\n<p>Si, au contraire, vous d\u00e9cochez les cases \u00ab&nbsp;Ajouter un second cation&nbsp;\u00bb et \u00ab&nbsp;Ajouter un second anion&nbsp;\u00bb, les m\u00eames donn\u00e9es se r\u00e9duisent au cas du NaCl : \\(\\Lambda^\\circ_m(\\text{NaCl}) = 50.11 + 76.35 = 126.46\\) S\u00b7cm\u00b2\/mol, la valeur tabul\u00e9e commun\u00e9ment admise.<\/p>\n<p>\n\r\n<\/section>\n<h2>Comment utiliser le calculateur<\/h2>\n<ol>\n<li>Saisissez le <strong>nom du cation<\/strong> (facultatif, utilis\u00e9 pour l'\u00e9tiquetage) et sa <strong>conductivit\u00e9 molaire limite (\u03bb\u00b0\u208a)<\/strong> en S\u00b7cm\u00b2\/mol, par exemple 50,11 pour Na\u207a.<\/li>\n<li>D\u00e9finissez le <strong>coefficient st\u0153chiom\u00e9trique (\u03bd\u208a)<\/strong> du cation \u2014 le nombre de cations de ce type par unit\u00e9 formulaire, par exemple 2 pour Na\u207a dans Na\u2082SO\u2084.<\/li>\n<li>Si le sel comporte deux cations diff\u00e9rents (par exemple KAl(SO\u2084)\u2082), cochez <strong>Ajouter un second cation<\/strong> et renseignez le nom, la \u03bb\u00b0 et le coefficient du second cation&nbsp;; sinon laissez la case d\u00e9coch\u00e9e.<\/li>\n<li>Proc\u00e9dez de la m\u00eame fa\u00e7on pour l'anion&nbsp;: <strong>nom de l'anion<\/strong>, <strong>conductivit\u00e9 molaire limite (\u03bb\u00b0\u208b)<\/strong>, <strong>coefficient st\u0153chiom\u00e9trique (\u03bd\u208b)<\/strong> et, si n\u00e9cessaire, <strong>Ajouter un second anion<\/strong>.<\/li>\n<li>Choisissez l'<strong>unit\u00e9 de sortie<\/strong> \u2014 S\u00b7cm\u00b2\/mol (l'unit\u00e9 utilis\u00e9e dans la plupart des tables de donn\u00e9es) ou S\u00b7m\u00b2\/mol (l'unit\u00e9 du Syst\u00e8me international).<\/li>\n<li>Lisez le r\u00e9sultat&nbsp;: la <strong>conductivit\u00e9 molaire limite (\u039b\u00b0\u2098)<\/strong>, la r\u00e9partition des contributions ion par ion et la substitution compl\u00e8te s'affichent imm\u00e9diatement.<\/li>\n<\/ol>\n<h2>Qu'est-ce que la loi de Kohlrausch sur la migration ind\u00e9pendante des ions ?<\/h2>\n<p>Lorsqu'on applique un champ \u00e9lectrique \u00e0 une solution d'\u00e9lectrolyte, cations et anions migrent et transportent le courant. Friedrich Kohlrausch a d\u00e9couvert (vers 1875) qu'\u00e0 <em>dilution infinie<\/em> \u2014 lorsque les ions sont si \u00e9loign\u00e9s les uns des autres qu'ils n'interagissent plus \u2014 chaque ion migre ind\u00e9pendamment de son contre-ion. La conductivit\u00e9 molaire de l'\u00e9lectrolyte tout entier est donc simplement la somme des conductivit\u00e9s ioniques individuelles, chacune multipli\u00e9e par le nombre d'ions de ce type produits par l'unit\u00e9 formulaire lors de la dissociation.<\/p>\n<p>Une preuve exp\u00e9rimentale classique est la r\u00e8gle des diff\u00e9rences : \\(\\Lambda^\\circ_m(\\text{KCl}) - \\Lambda^\\circ_m(\\text{NaCl})\\) est \u00e9gal \u00e0 \\(\\Lambda^\\circ_m(\\text{KBr}) - \\Lambda^\\circ_m(\\text{NaBr})\\), car la contribution de l'anion s'annule et seule subsiste la diff\u00e9rence entre K\u207a et Na\u207a. C'est exactement cette additivit\u00e9 que le calculateur reproduit.<\/p>\n<p>Cette loi est particuli\u00e8rement pr\u00e9cieuse pour les <strong>\u00e9lectrolytes faibles<\/strong> comme l'acide ac\u00e9tique. Les \u00e9lectrolytes forts ob\u00e9issent \u00e0 la loi en racine carr\u00e9e de Kohlrausch \\(\\Lambda_m = \\Lambda^\\circ_m - K\\sqrt{c}\\) : leur conductivit\u00e9 limite peut donc \u00eatre obtenue en extrapolant les valeurs mesur\u00e9es jusqu'\u00e0 concentration nulle. Les \u00e9lectrolytes faibles, eux, restent presque enti\u00e8rement associ\u00e9s m\u00eame \u00e0 faible concentration, et l'extrapolation \u00e9choue \u2014 mais la loi de Kohlrausch donne directement la r\u00e9ponse : \\(\\Lambda^\\circ_m(\\text{CH}_3\\text{COOH}) = \\lambda^\\circ(\\text{H}^+) + \\lambda^\\circ(\\text{CH}_3\\text{COO}^-) = 349.65 + 40.9 \\approx 390.6\\) S\u00b7cm\u00b2\/mol.<\/p>\n<p>Une fois \\(\\Lambda^\\circ_m\\) connu, sa comparaison avec une conductivit\u00e9 molaire mesur\u00e9e \\(\\Lambda_m\\) \u00e0 la concentration \\(c\\) donne le degr\u00e9 de dissociation \\(\\alpha = \\Lambda_m \/ \\Lambda^\\circ_m\\) \u2014 la voie classique des exercices sur la constante de dissociation et la solubilit\u00e9. Notre <a href=\"https:\/\/wpcalc.com\/fr\/chimie\/calculateur-conductivite-molaire\/\">calculateur de conductivit\u00e9 molaire<\/a> traite l'\u00e9tape \\(\\Lambda_m = \\kappa \/ c\\), et le <a href=\"https:\/\/wpcalc.com\/fr\/chimie\/calculateur-produit-de-solubilite-ksp\/\">calculateur de produit de solubilit\u00e9<\/a> couvre les applications aux sels peu solubles.<\/p>\n<h2>Hypoth\u00e8ses et limites<\/h2>\n<ul>\n<li><strong>Dilution infinie&nbsp;:<\/strong> la loi n'est rigoureusement valable qu'\u00e0 la limite \\(c \\to 0\\). Aux concentrations r\u00e9elles, les interactions entre ions (atmosph\u00e8res ioniques) abaissent \\(\\Lambda_m\\) sous \\(\\Lambda^\\circ_m\\) ; pour les \u00e9lectrolytes forts, cela suit \\(\\Lambda_m = \\Lambda^\\circ_m - K\\sqrt{c}\\). Pour savoir comment les activit\u00e9s s'\u00e9cartent des valeurs id\u00e9ales \u00e0 concentration finie, consultez le <a href=\"https:\/\/wpcalc.com\/fr\/chimie\/coefficient-activite-debye-huckel\/\">calculateur de coefficient d'activit\u00e9 de Debye\u2013H\u00fcckel<\/a>.<\/li>\n<li><strong>Temp\u00e9rature&nbsp;:<\/strong> les valeurs \u03bb\u00b0 des tables se r\u00e9f\u00e8rent \u00e0 25 \u00b0C dans l'eau. La conductivit\u00e9 augmente d'environ 2 \u00e0 3\u00a0% par degr\u00e9 : utilisez donc des valeurs mesur\u00e9es \u00e0 votre temp\u00e9rature si une grande pr\u00e9cision est n\u00e9cessaire.<\/li>\n<li><strong>Par mole d'ions&nbsp;:<\/strong> \u03bb\u00b0 est d\u00e9fini par mole d'ions telle qu'\u00e9crite, et non par unit\u00e9 de charge. Pour Ca\u00b2\u207a, \u03bb\u00b0 = 119,0 S\u00b7cm\u00b2\/mol tient d\u00e9j\u00e0 compte de la double charge \u2014 ne multipliez pas \u00e0 nouveau par 2.<\/li>\n<li><strong>Neutralit\u00e9 \u00e9lectrique&nbsp;:<\/strong> les coefficients st\u0153chiom\u00e9triques doivent d\u00e9crire une unit\u00e9 formulaire \u00e9lectriquement neutre (\\(\\sum \\nu_+ z_+ = \\sum \\nu_- z_-\\)), sinon le \u00ab\u00a0sel\u00a0\u00bb saisi ne peut pas exister et la somme n'a aucun sens.<\/li>\n<li><strong>Dissociation compl\u00e8te \u00e0 dilution infinie&nbsp;:<\/strong> m\u00eame les \u00e9lectrolytes faibles sont consid\u00e9r\u00e9s comme totalement dissoci\u00e9s \u00e0 la limite \\(c \\to 0\\) ; la dissociation partielle n'intervient qu'\u00e0 concentration finie.<\/li>\n<li><strong>Conversion d'unit\u00e9s&nbsp;:<\/strong> 1 S\u00b7cm\u00b2\/mol = 10\u207b\u2074 S\u00b7m\u00b2\/mol. Les tables de donn\u00e9es utilisent presque toujours le S\u00b7cm\u00b2\/mol, qui est l'unit\u00e9 d'entr\u00e9e par d\u00e9faut du calculateur.<\/li>\n<\/ul>\n<h2>R\u00e9f\u00e9rence : conductivit\u00e9s molaires limites des ions courants (25 \u00b0C, S\u00b7cm\u00b2\/mol)<\/h2>\n<table>\n<thead>\n<tr>\n<th>Cation<\/th>\n<th>\u03bb\u00b0<\/th>\n<th>Anion<\/th>\n<th>\u03bb\u00b0<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>H\u207a<\/td>\n<td>349,65<\/td>\n<td>OH\u207b<\/td>\n<td>198,3<\/td>\n<\/tr>\n<tr>\n<td>Li\u207a<\/td>\n<td>38,7<\/td>\n<td>Cl\u207b<\/td>\n<td>76,35<\/td>\n<\/tr>\n<tr>\n<td>Na\u207a<\/td>\n<td>50,11<\/td>\n<td>Br\u207b<\/td>\n<td>78,1<\/td>\n<\/tr>\n<tr>\n<td>K\u207a<\/td>\n<td>73,5<\/td>\n<td>I\u207b<\/td>\n<td>76,8<\/td>\n<\/tr>\n<tr>\n<td>NH\u2084\u207a<\/td>\n<td>73,5<\/td>\n<td>NO\u2083\u207b<\/td>\n<td>71,5<\/td>\n<\/tr>\n<tr>\n<td>Ag\u207a<\/td>\n<td>61,9<\/td>\n<td>HCO\u2083\u207b<\/td>\n<td>44,5<\/td>\n<\/tr>\n<tr>\n<td>Mg\u00b2\u207a<\/td>\n<td>106,1<\/td>\n<td>CH\u2083COO\u207b<\/td>\n<td>40,9<\/td>\n<\/tr>\n<tr>\n<td>Ca\u00b2\u207a<\/td>\n<td>119,0<\/td>\n<td>SO\u2084\u00b2\u207b<\/td>\n<td>160,0<\/td>\n<\/tr>\n<tr>\n<td>Ba\u00b2\u207a<\/td>\n<td>127,2<\/td>\n<td>\u00bdSO\u2084\u00b2\u207b (par \u00e9quivalent)<\/td>\n<td>80,0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Utilisez directement ces valeurs dans les champs \u03bb\u00b0 du calculateur. Notez les valeurs remarquablement \u00e9lev\u00e9es de H\u207a et OH\u207b \u2014 une cons\u00e9quence du m\u00e9canisme de saut de proton de Grotthuss dans l'eau, qui explique aussi pourquoi les acides et les bases fortes conduisent bien mieux le courant que leurs sels.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Calculez la conductivit\u00e9 molaire limite de tout \u00e9lectrolyte \u00e0 dilution infinie \u00e0 partir des conductivit\u00e9s ioniques et des coefficients st\u0153chiom\u00e9triques, gr\u00e2ce \u00e0 la loi de Kohlrausch sur la migration ind\u00e9pendante des ions.<\/p>\n","protected":false},"author":3168,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[17],"tags":[40],"class_list":["post-5853","post","type-post","status-publish","format-standard","hentry","category-chimie","tag-stoechiometrie"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/posts\/5853","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/users\/3168"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/comments?post=5853"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/posts\/5853\/revisions"}],"predecessor-version":[{"id":5945,"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/posts\/5853\/revisions\/5945"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/media?parent=5853"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/categories?post=5853"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/fr\/wp-json\/wp\/v2\/tags?post=5853"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}