{"id":10475,"date":"2026-09-26T11:30:25","date_gmt":"2026-09-26T10:30:25","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/disproportionation\/"},"modified":"2026-10-04T23:02:35","modified_gmt":"2026-10-04T22:02:35","slug":"disproportionation","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/disproportionation\/","title":{"rendered":"Disproportionation"},"content":{"rendered":"\n<section class=\"ols-revision-page ols-redox-groups-page\">\n  <style>\n    .ols-revision-page {\n      --navy: #1C244B;\n      --blue: #2563eb;\n      --soft-blue: #eef4ff;\n      --soft-red: #fff7f7;\n      --soft-purple: #f7f0ff;\n      --soft-green: #f0f7f1;\n      --gold: #c9973a;\n      --grey-text: #667085;\n 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   margin: 0 0 8px;\n      font-size: 20px;\n      line-height: 1.3;\n      color: var(--navy);\n    }\n.ols-faq-item p {\n      margin: 0;\n      font-size: 16px;\n      line-height: 1.65;\n      color: var(--body-text);\n    }\n.ols-faq-card,\n      .ols-quicksnap-card,\n      .ols-attribution-card {\n        padding: 24px 18px;\n        border-radius: 22px;\n      }\n  <\/style>\n\n    <aside class=\"ols-sidebar\">\n  <div class=\"ols-sidebar-header\">\n    <h3>Revision Notes<\/h3>\n    <p>A Level Chemistry<\/p>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>Topic 8 Redox &amp; Groups 1, 2 and 7<\/h4>\n\n    <ul class=\"ols-topic-list\">\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/\">Topic 8 Overview<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/\">Topic 8A Redox Chemistry<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/oxidation-numbers\/\">Oxidation Numbers<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/electron-transfer-and-half-equations\/\">Electron Transfer and Half-Equations<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/disproportionation\/\">Disproportionation<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/redox-classification\/\">Redox Classification<\/a>\n          <\/li>\n        <\/ul>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/\">Topic 8B Groups 1 and 2<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/trends-down-groups-1-and-2\/\">Trends Down Groups 1 and 2<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/reactions-of-the-group-1-and-2-elements\/\">Reactions of the Group 1 and 2 Elements<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/oxides-hydroxides-and-carbonates\/\">Oxides, Hydroxides and Carbonates<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/solubility-trends-and-the-sulfate-test\/\">Solubility Trends and the Sulfate Test<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/\">Thermal Stability and Flame Colours<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/tests-for-ions\/\">Tests for Ions<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/titrations-and-measurement-uncertainty\/\">Titrations and Measurement Uncertainty<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-3-concentration-of-hcl-by-titration\/\">Core Practical 3<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-4-preparation-of-a-standard-solution\/\">Core Practical 4<\/a>\n          <\/li>\n        <\/ul>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/\">Topic 8C Group 7<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/trends-in-the-halogens\/\">Trends in the Halogens<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/halogens-as-oxidising-agents\/\">Halogens as Oxidising Agents<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/disproportionation-reactions-of-chlorine\/\">Disproportionation Reactions of Chlorine<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/halide-ions-reducing-agents-and-tests\/\">Halide Ions: Reducing Agents and Tests<\/a>\n          <\/li>\n        <\/ul>\n      <\/li>\n    <\/ul>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>Other Topics<\/h4>\n\n    <ul class=\"ols-topic-list\">\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-6-energetics\/\">Topic 6 Energetics<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-7-intermolecular-forces\/\">Topic 7 Intermolecular Forces<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-2-atomic-structure-and-the-periodic-table\/\">Topic 2 Atomic Structure &amp; The Periodic Table<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/\">Core Practicals<\/a>\n      <\/li>\n    <\/ul>\n  <\/div>\n<\/aside>\n\n<script>\r\n(function() {\r\n  function normalisePath(path) {\r\n    return String(path || '')\r\n      .split('?')[0]\r\n      .split('#')[0]\r\n      .replace(\/\\\/+$\/, '')\r\n      .toLowerCase();\r\n  }\r\n\r\n  function highlightActive() {\r\n    var sidebar = document.querySelector('.ols-sidebar');\r\n    if (!sidebar) return false;\r\n\r\n    var currentPath = normalisePath(window.location.pathname);\r\n    var links = sidebar.querySelectorAll('a[href]');\r\n    var matched = null;\r\n    var matchedLength = 0;\r\n\r\n    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href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/\">Topic 8 Redox Chemistry and Groups 1, 2 and 7<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/\">Topic 8A Redox Chemistry<\/a> \/\n<span>Disproportionation<\/span>\n<\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Disproportionation<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to disproportionation: one element in a single species oxidised and reduced at the same time, how to spot it with oxidation numbers, the chlorine and hydrogen peroxide examples, and which species can and cannot disproportionate.<\/p>\n        <div class=\"ols-badges\">\n<div class=\"ols-badge\">Exam board: Edexcel International<\/div>\n<div class=\"ols-badge\">Unit 2: WCH12\/01<\/div>\n<div class=\"ols-badge\">Topic 8A Redox Chemistry<\/div>\n<\/div>\n        <div class=\"ols-author\">\n\n    <img decoding=\"async\"\n      class=\"ols-author-avatar-img\"\n      src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Author-Profile.jpeg\"\n      alt=\"Dr. Mohammed Al-Fatah\"\n    >\n\n    <div class=\"ols-author-content\">\n\n      <h2 class=\"ols-author-title\">\n        Written by: Dr. Mohammed Al-Fatah\n      <\/h2>\n\n      <p class=\"ols-author-description\">\n        Chemistry specialist revision notes for A Level Chemistry.\n      <\/p>\n\n      <a class=\"ols-linkedin-pill\" href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n        <svg class=\"ols-linkedin-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\">\n          <path d=\"M4.98 3.5C4.98 4.88 3.86 6 2.48 6S0 4.88 0 3.5 1.12 1 2.48 1s2.5 1.12 2.5 2.5zM.5 8h4V24h-4V8zm7 0h3.8v2.2h.1c.5-.9 1.8-2.2 3.9-2.2 4.2 0 5 2.8 5 6.4V24h-4v-7.6c0-1.8 0-4.2-2.6-4.2s-3 2-3 4v7.8h-4V8z\"\/>\n        <\/svg>\n        View LinkedIn Profile\n      <\/a>\n\n    <\/div>\n\n  <\/div>\n      <\/header>\n\n      <article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">1<\/div>\n<h2>What Disproportionation Is<\/h2>\n<\/div>\n<p><strong>Disproportionation<\/strong> is a redox reaction in which the <strong>same element<\/strong> in a <strong>single species<\/strong> is both oxidised and reduced at the same time.<\/p>\n<p>Some of the atoms of that element go up in oxidation number while others go down. The element must be in an intermediate oxidation number to begin with, so that it has room to move in both directions.<\/p>\n<p>Chlorine gas reacting with water is the classic case. Chlorine starts at 0; in the products it is \u22121 in hydrochloric acid and +1 in chloric(I) acid:<\/p>\n<p>Cl\u2082(g) + H\u2082O(l) \u21cc HCl(aq) + HClO(aq)<\/p>\n<p>One chlorine atom has been reduced (0 to \u22121) and the other oxidised (0 to +1). Chlorine is both the oxidising agent and the reducing agent.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Definition:<\/strong> A disproportionation reaction is one in which an element in a single species is simultaneously oxidised and reduced.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">2<\/div>\n<h2>Spotting It with Oxidation numbers<\/h2>\n<\/div>\n<p>To decide whether a reaction is a disproportionation, assign oxidation numbers to every atom on both sides and look for one element that appears at one value on the left and at two different values on the right, one higher and one lower.<\/p>\n<div class=\"ols-figure-card ols-zoom-pop\">\n<div class=\"ols-figure-image\">\n<a class=\"ols-image-fullscreen-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/redox-groups-disproportionation-chlorine-ladder.png\" target=\"_blank\" rel=\"noopener\" aria-label=\"Open image fullscreen\">\n<img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/redox-groups-disproportionation-chlorine-ladder.png\" alt=\"Oxidation-number ladder for chlorine showing Cl2 disproportionating in water\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/redox-groups-disproportionation-chlorine-ladder.png\">\n<\/a>\n<\/div>\n<div class=\"ols-figure-caption\"><p>From the 0 rung, chlorine goes down to \u22121 and up to +1 at the same time, which is the pattern that defines disproportionation.<\/p><\/div>\n<\/div>\n<p><strong>Worked example:<\/strong> copper(I) ions in solution. 2Cu\u207a(aq) \u2192 Cu(s) + Cu\u00b2\u207a(aq). Copper starts at +1 and finishes at 0 (reduced) and +2 (oxidised). This is disproportionation, and it is why copper(I) sulfate cannot exist in water.<\/p>\n<p><strong>Worked example:<\/strong> hydrogen peroxide decomposing. 2H\u2082O\u2082 \u2192 2H\u2082O + O\u2082. Oxygen starts at \u22121 and finishes at \u22122 in water (reduced) and 0 in oxygen gas (oxidised). Disproportionation again.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Exam focus:<\/strong> Write the oxidation number above every atom of the element concerned on both sides, then state both changes with their numbers: &#8220;chlorine is reduced from 0 to \u22121 and oxidised from 0 to +1&#8221;.<\/p>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Check: Is It Disproportionation?<\/h2>\n<p>Assign oxidation numbers in reactions not shown above and decide which are disproportionation.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-858\" class=\"h5p-iframe\" data-content-id=\"858\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Redox and Groups Quick Choice: Is It Disproportionation?\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card purple\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">3<\/div>\n<h2>Why Chlorine Disproportionates<\/h2>\n<\/div>\n<p>Chlorine sits at 0, and it forms stable compounds both below (chloride, \u22121) and above (chlorate(I) +1, chlorate(V) +5). A reaction that sends some atoms each way can therefore be favourable.<\/p>\n<p>Which higher state forms depends on the conditions. With water or cold dilute alkali chlorine reaches +1, but with hot concentrated alkali it goes to +5, forming chlorate(V) ions, ClO\u2083\u207b, alongside chloride.<\/p>\n<p>These reactions are so important in water treatment and bleach manufacture that they have a page of their own in the Group 7 section: <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/disproportionation-reactions-of-chlorine\/\">Disproportionation Reactions of Chlorine<\/a>. Here the point is the pattern, not the industrial detail.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Key idea:<\/strong> An element can only disproportionate if it is in an intermediate oxidation number. Fluorine cannot, because it has no positive oxidation numbers; sodium cannot, because it has no negative ones.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">4<\/div>\n<h2>The Reverse Process<\/h2>\n<\/div>\n<p>The reverse of disproportionation is called <strong>comproportionation<\/strong>. Two species containing the same element at different oxidation numbers react to give one product at an intermediate value.<\/p>\n<p>Iodate(V) ions and iodide ions in acid give iodine: IO\u2083\u207b + 5I\u207b + 6H\u207a \u2192 3I\u2082 + 3H\u2082O. Iodine goes from +5 and \u22121 to 0.<\/p>\n<p>The name is rarely examined, but recognising the pattern helps when an unfamiliar equation appears.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Remember:<\/strong> Disproportionation: one element, one starting value, two finishing values. Comproportionation: one element, two starting values, one finishing value.<\/p>\n<\/div>\n<div class=\"ols-figure-card ols-zoom-pop\">\n<div class=\"ols-figure-image\">\n<a class=\"ols-image-fullscreen-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/t8x-comprop.jpg\" target=\"_blank\" rel=\"noopener\" aria-label=\"Open image fullscreen\">\n<img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/t8x-comprop.jpg\" alt=\"Two-column poster comparing disproportionation of Cu\u207a and H\u2082O\u2082 with comproportionation of iodate(V) and iodide.\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/t8x-comprop.jpg\">\n<\/a>\n<\/div>\n<div class=\"ols-figure-caption\"><p>In disproportionation one starting oxidation number splits into two; in comproportionation two starting values meet at one, as when iodate(V) and iodide ions give iodine.<\/p><\/div>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Check: Which Elements Can Disproportionate?<\/h2>\n<p>Use the idea of intermediate oxidation numbers to decide which of a list of species could disproportionate.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-859\" class=\"h5p-iframe\" data-content-id=\"859\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Redox and Groups MCQ: Which Species Could Disproportionate?\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">5<\/div>\n<h2>Common Exam Points<\/h2>\n<\/div>\n<h3>Define disproportionation<\/h3><p>A reaction in which an element in a single species is simultaneously oxidised and reduced.<\/p>\n<h3>Show that a reaction is a disproportionation<\/h3><p>Give the oxidation number of the element in the reactant and in each product, and state which change is oxidation and which is reduction.<\/p>\n<h3>Do not say<\/h3><p>&#8220;Two different elements are oxidised and reduced&#8221; (that is ordinary redox); &#8220;chlorine is neutralised&#8221;; &#8220;the oxidation number of chlorine in HClO is \u22121&#8221;.<\/p>\n<\/article>\n<section class=\"ols-faq-card\">\n<h2>FAQs<\/h2>\n<p>Use these quick answers to check the disproportionation idea.<\/p>\n\n<div class=\"ols-faq-list\">\n<div class=\"ols-faq-item\">\n<h3>What is disproportionation?<\/h3>\n<p>A redox reaction in which the same element in one species is both oxidised and reduced at the same time.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>How do I recognise it in an equation?<\/h3>\n<p>Assign oxidation numbers. If one element starts at a single value and finishes at two different values, one higher and one lower, the reaction is a disproportionation.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>Why can chlorine disproportionate but fluorine cannot?<\/h3>\n<p>Chlorine starts at 0 and has stable oxidation numbers both above and below it. Fluorine has no positive oxidation numbers, so it can only be reduced.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>Is the reaction of chlorine with water reversible?<\/h3>\n<p>Yes. Chlorine water contains chlorine, hydrochloric acid and chloric(I) acid in equilibrium. With alkali the acids are neutralised and the reaction goes to completion.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>Is a reaction where two different elements are oxidised and reduced a disproportionation?<\/h3>\n<p>No. That is an ordinary redox reaction. Disproportionation needs the same element going both ways.<\/p>\n<\/div>\n<\/div>\n<\/section>\n<section class=\"ols-related-card\">\n<h2>Related Topic 8A Redox Chemistry Pages<\/h2>\n<p>Use these pages to connect the ideas across redox chemistry and the rest of Topic 8.<\/p>\n<div class=\"ols-related-grid\">\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/oxidation-numbers\/\">Oxidation Numbers<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/electron-transfer-and-half-equations\/\">Electron Transfer and Half-Equations<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/redox-classification\/\">Redox Classification<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/\">Topic 8A Redox Chemistry Overview<\/a>\n<\/div>\n<\/section>\n<section class=\"ols-attribution-card\">\n        <p><strong>Copyright notice:<\/strong> This OLS revision content, including the explanations, layout, diagrams, tables and embedded learning structure, is authored for Online Learning System by Dr. Mohammed Al-Fatah. It may not be copied, reproduced, redistributed or adapted without written permission.<\/p>\n      <\/section>\n    <\/main>\n  \n\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@graph\": [\n    {\n      \"@type\": \"WebPage\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/disproportionation\/#webpage\",\n      \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/disproportionation\/\",\n      \"name\": \"Disproportionation | Topic 8A Redox Chemistry | Online Learning System\",\n      \"description\": \"Edexcel International A Level Chemistry revision notes on disproportionation: recognising it with oxidation numbers, chlorine in water and alkali, hydrogen peroxide, copper(I) and 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