{"id":4742,"date":"2026-06-02T07:46:48","date_gmt":"2026-06-02T06:46:48","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/typical-reactions-of-acids\/"},"modified":"2026-06-28T05:51:13","modified_gmt":"2026-06-28T04:51:13","slug":"typical-reactions-of-acids","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/typical-reactions-of-acids\/","title":{"rendered":"Typical Reactions of Acids"},"content":{"rendered":"\n<!--\n===============================================================================\nONLINE LEARNING SYSTEM COPYRIGHT NOTICE\n\u00a9 Online Learning System. All rights reserved.\n\nThis WordPress revision page HTML, CSS, content sequence, educational wording,\nlayout structure, schema structure and embedded design logic are protected\nintellectual property of Online Learning System.\n\nUnauthorised copying, redistribution, resale, modification, republication,\nscraping, extraction, derivative reuse, automated harvesting or removal of\ncopyright notices is strictly prohibited.\n\nBackend copyright marker:\nOLS-T5-TYPICAL-REACTIONS-OF-ACIDS-REVISION-PAGE-2026\n\nPage:\nTypical Reactions of Acids\nEdexcel A Level Chemistry\nUnit: Paper 1\nTopic 5: Formulae, Equations and Amounts of Substance\n9CH0\/01\n\nCopyright enforcement notes:\n- The visible student page is a free OLS revision resource.\n- The backend HTML structure, CSS architecture, card sequencing, schema graph,\n  revision wording, responsive table behaviour and embedded learning pathway are\n  proprietary OLS production assets.\n- Do not remove this notice.\n===============================================================================\n-->\n\n<section class=\"ols-revision-page ols-typical-reactions-of-acids-page\" data-owner=\"Online Learning System\" data-copyright=\"\u00a9 Online Learning System. 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max-height: 88vh;\n        border-radius: 16px;\n      }\n\n      .ols-image-lightbox-close {\n        top: 10px;\n        right: 10px;\n        width: 42px;\n        height: 42px;\n        font-size: 26px;\n      }\n    }\n\n  <\/style>\n\n  <!--\n    OLS protected content block.\n    Page: Typical Reactions of Acids.\n    This content is authored for Online Learning System and must not be scraped,\n    cloned, republished, resold, reformatted into derivative notes, or reused in\n    competing resources without written permission.\n  -->\n\n  <div class=\"ols-revision-layout\">\n    <aside class=\"ols-sidebar\">\r\n  <div class=\"ols-sidebar-header\">\r\n    <h3>Revision Notes<\/h3>\r\n    <p>A Level Chemistry<\/p>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Topic 5 Formulae, Equations and Amounts of Substance<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/atoms-elements-and-molecules\/\">Atoms, Elements and Molecules<\/a>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/\">Equations and Reaction Types<\/a>\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/writing-chemical-equations\/\">Writing Chemical Equations<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/typical-reactions-of-acids\/\">Typical Reactions of Acids<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/ionic-and-full-equations\/\">Ionic and Full Equations<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/mole-calculations\/\">Mole Calculations<\/a>\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/mole-calculations\/comparing-masses-of-substances\/\">Comparing Masses of Substances<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/mole-calculations\/calculations-involving-moles\/\">Calculations involving Moles<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/mole-calculations\/calculations-using-reacting-masses\/\">Calculations using Reacting Masses<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/mole-calculations\/the-yield-of-a-reaction\/\">The Yield of a Reaction<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/mole-calculations\/atom-economy\/\">Atom Economy<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/empirical-and-molecular-formulae\/\">Empirical and Molecular Formulae<\/a>\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/empirical-and-molecular-formulae\/empirical-formulae\/\">Empirical Formulae<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/empirical-and-molecular-formulae\/molecular-formulae\/\">Molecular Formulae<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/calculations-with-solutions-and-gases\/\">Calculations with Solutions and Gases<\/a>\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/calculations-with-solutions-and-gases\/molar-volume-calculations\/\">Molar Volume Calculations<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/calculations-with-solutions-and-gases\/concentrations-of-solutions\/\">Concentrations of Solutions<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/calculations-with-solutions-and-gases\/titration-calculations\/\">Titration Calculations<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/measurement-uncertainty-and-errors\/\">Measurement Uncertainty and Errors<\/a>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/risks-hazards-and-practical-precautions\/\">Risks, Hazards and Practical Precautions<\/a>\r\n      <\/li>\r\n\r\n    <\/ul>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Next Topics<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/\">Topic 6 Organic Chemistry I<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-7-modern-analytical-techniques-i\/\">Topic 7 Modern Analytical Techniques I<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-4-inorganic-chemistry-and-the-periodic-table\/\">Topic 4 Inorganic Chemistry &amp; The Periodic Table<\/a>\r\n      <\/li>\r\n    <\/ul>\r\n  <\/div>\r\n<\/aside>\r\n\r\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   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Formulae, Equations and Amounts of Substance<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/\">Equations and Reaction Types<\/a> \/\n        <span>Typical Reactions of Acids<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Typical Reactions of Acids<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to the common reactions of acids, including acid-base neutralisation, acid-metal reactions, acid-carbonate reactions and the ionic equations that show the particles actually reacting.<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Unit: Paper 1<\/div>\n          <div class=\"ols-badge\">Topic 5: Formulae, Equations and Amounts of Substance<\/div>\n          <div class=\"ols-badge\">9CH0\/01<\/div>\n        <\/div>\n\n        <div class=\"ols-author\">\n          <img decoding=\"async\" class=\"ols-author-avatar-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Author-Profile.jpeg\" alt=\"Dr. Mohammed Al-Fatah\">\n          <div class=\"ols-author-content\">\n            <h2 class=\"ols-author-title\">Written by:<br><span>Dr. Mohammed Al-Fatah<\/span><\/h2>\n            <p class=\"ols-author-description\">Chemistry specialist revision notes for A Level Chemistry.<\/p>\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\"><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\"><\/path><\/svg>\n              View LinkedIn Profile\n            <\/a>\n          <\/div>\n        <\/div>\n      <\/header>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">1<\/div><h2>What Acids Do in Reactions<\/h2><\/div>\n        <p>In aqueous solution, acids provide <strong>H<sup>+<\/sup> ions<\/strong>. These hydrogen ions are responsible for the typical reactions of acids.<\/p>\n        <p>The common strong acids used in many school-level reactions are <strong>hydrochloric acid, HCl<\/strong>, <strong>sulfuric acid, H<sub>2<\/sub>SO<sub>4<\/sub><\/strong>, and <strong>nitric acid, HNO<sub>3<\/sub><\/strong>.<\/p>\n        <div class=\"ols-definition-box\"><p><strong>Acid reaction pattern:<\/strong> the acid supplies H<sup>+<\/sup> ions, while the other reactant determines the type of product formed.<\/p><\/div>\n        <div class=\"ols-key-box\"><p><strong>Key idea:<\/strong> acid reactions often look different as full equations, but their ionic equations can reveal the same underlying particle change.<\/p><\/div>\n      <\/article>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">2<\/div><h2>Acids, Bases and Alkalis<\/h2><\/div>\n        <p>A <strong>base<\/strong> neutralises an acid. Common bases include <strong>metal oxides<\/strong>, <strong>metal hydroxides<\/strong> and <strong>ammonia<\/strong>.<\/p>\n        <p>An <strong>alkali<\/strong> is a soluble base that releases <strong>OH<sup>&#8211;<\/sup> ions<\/strong> in aqueous solution. Common alkalis include sodium hydroxide, NaOH, potassium hydroxide, KOH, and aqueous ammonia, NH<sub>3<\/sub>.<\/p>\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Term<\/th>\n                <th>Meaning<\/th>\n                <th>Examples<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Term\">Base<\/td>\n                <td data-label=\"Meaning\">A substance that neutralises an acid.<\/td>\n                <td data-label=\"Examples\">Metal oxides, metal hydroxides and ammonia.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Term\">Alkali<\/td>\n                <td data-label=\"Meaning\">A soluble base that releases OH<sup>&#8211;<\/sup> ions in water.<\/td>\n                <td data-label=\"Examples\">NaOH, KOH and aqueous NH<sub>3<\/sub>.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Term\">Salt<\/td>\n                <td data-label=\"Meaning\">A compound formed when the H<sup>+<\/sup> ion of an acid is replaced by a metal ion or ammonium ion.<\/td>\n                <td data-label=\"Examples\">NaCl, MgSO<sub>4<\/sub> and NH<sub>4<\/sub>Cl.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">3<\/div><h2>Neutralisation Reactions Form Salts<\/h2><\/div>\n        <p><strong>Neutralisation<\/strong> is the reaction between an acid and a base. The acid is neutralised because the H<sup>+<\/sup> ions are removed by reacting with basic particles such as OH<sup>&#8211;<\/sup> ions.<\/p>\n        <p>When an acid reacts with a metal hydroxide, the products are usually a <strong>salt<\/strong> and <strong>water<\/strong>.<\/p>\n        <div class=\"ols-definition-box\"><p><strong>General equation:<\/strong> acid + metal hydroxide \u2192 salt + water<\/p><\/div>\n        <div class=\"ols-definition-box\"><p><strong>Example:<\/strong> HCl(aq) + NaOH(aq) \u2192 NaCl(aq) + H<sub>2<\/sub>O(l)<\/p><\/div>\n        <p>The ionic equation for neutralisation is the same for many acid-alkali reactions because H<sup>+<\/sup> ions react with OH<sup>&#8211;<\/sup> ions to form water.<\/p>\n        <div class=\"ols-key-box\"><p><strong>Ionic equation:<\/strong> H<sup>+<\/sup>(aq) + OH<sup>&#8211;<\/sup>(aq) \u2192 H<sub>2<\/sub>O(l)<\/p><\/div>\n      <\/article>\n\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">4<\/div><h2>Acids Reacting with Metals<\/h2><\/div>\n        <p>Reactive metals such as magnesium react with dilute acids to form a <strong>salt<\/strong> and <strong>hydrogen gas<\/strong>. The hydrogen gas is observed as fizzing or effervescence.<\/p>\n        <div class=\"ols-definition-box\"><p><strong>General equation:<\/strong> acid + metal \u2192 salt + hydrogen<\/p><\/div>\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Reaction<\/th>\n                <th>Full equation<\/th>\n                <th>Main observation<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Reaction\">Magnesium with hydrochloric acid<\/td>\n                <td data-label=\"Full equation\">Mg(s) + 2HCl(aq) \u2192 MgCl<sub>2<\/sub>(aq) + H<sub>2<\/sub>(g)<\/td>\n                <td data-label=\"Main observation\">Fizzing as hydrogen gas forms.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Reaction\">Magnesium with sulfuric acid<\/td>\n                <td data-label=\"Full equation\">Mg(s) + H<sub>2<\/sub>SO<sub>4<\/sub>(aq) \u2192 MgSO<sub>4<\/sub>(aq) + H<sub>2<\/sub>(g)<\/td>\n                <td data-label=\"Main observation\">The metal disappears if the acid is in excess.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n        <p>The ionic equation is the same in both cases because chloride ions and sulfate ions are spectator ions. They do not change during the reaction.<\/p>\n        <div class=\"ols-key-box\"><p><strong>Ionic equation:<\/strong> Mg(s) + 2H<sup>+<\/sup>(aq) \u2192 Mg<sup>2+<\/sup>(aq) + H<sub>2<\/sub>(g)<\/p><\/div>\n      <\/article>\n\n      <div class=\"ols-zoom-card\">\n        <div class=\"ols-zoom-card-image\">\n          <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Ionic-equations-for-acid-metal-reactions.webp\" alt=\"Ionic equations for reactions between acids and metals showing spectator ions\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>Different full equations can simplify to the same ionic equation when the spectator ions are removed.<\/p>\n        <\/div>\n      <\/div>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">5<\/div><h2>Acids Reacting with Metal Carbonates<\/h2><\/div>\n        <p>Metal carbonates react with dilute acids to form a <strong>salt<\/strong>, <strong>carbon dioxide<\/strong> and <strong>water<\/strong>. The carbon dioxide gas causes fizzing.<\/p>\n        <div class=\"ols-definition-box\"><p><strong>General equation:<\/strong> acid + metal carbonate \u2192 salt + carbon dioxide + water<\/p><\/div>\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Reaction<\/th>\n                <th>Full equation<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Reaction\">Calcium carbonate with hydrochloric acid<\/td>\n                <td data-label=\"Full equation\">CaCO<sub>3<\/sub>(s) + 2HCl(aq) \u2192 CaCl<sub>2<\/sub>(aq) + CO<sub>2<\/sub>(g) + H<sub>2<\/sub>O(l)<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Reaction\">Magnesium carbonate with nitric acid<\/td>\n                <td data-label=\"Full equation\">MgCO<sub>3<\/sub>(s) + 2HNO<sub>3<\/sub>(aq) \u2192 Mg(NO<sub>3<\/sub>)<sub>2<\/sub>(aq) + CO<sub>2<\/sub>(g) + H<sub>2<\/sub>O(l)<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Reaction\">Sodium carbonate with sulfuric acid<\/td>\n                <td data-label=\"Full equation\">Na<sub>2<\/sub>CO<sub>3<\/sub>(aq) + H<sub>2<\/sub>SO<sub>4<\/sub>(aq) \u2192 Na<sub>2<\/sub>SO<sub>4<\/sub>(aq) + CO<sub>2<\/sub>(g) + H<sub>2<\/sub>O(l)<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n        <p>For many acid-carbonate reactions, the useful ionic equation is:<\/p>\n        <div class=\"ols-key-box\"><p><strong>Ionic equation:<\/strong> CO<sub>3<\/sub><sup>2-<\/sup>(s or aq) + 2H<sup>+<\/sup>(aq) \u2192 CO<sub>2<\/sub>(g) + H<sub>2<\/sub>O(l)<\/p><\/div>\n      <\/article>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">6<\/div><h2>Choosing the Correct Salt Formula<\/h2><\/div>\n        <p>The name of the salt depends on the acid used and the positive ion supplied by the base, metal or carbonate.<\/p>\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Acid used<\/th>\n                <th>Salt type formed<\/th>\n                <th>Example salt<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Acid used\">Hydrochloric acid, HCl<\/td>\n                <td data-label=\"Salt type formed\">Chloride<\/td>\n                <td data-label=\"Example salt\">MgCl<sub>2<\/sub><\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Acid used\">Sulfuric acid, H<sub>2<\/sub>SO<sub>4<\/sub><\/td>\n                <td data-label=\"Salt type formed\">Sulfate<\/td>\n                <td data-label=\"Example salt\">MgSO<sub>4<\/sub><\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Acid used\">Nitric acid, HNO<sub>3<\/sub><\/td>\n                <td data-label=\"Salt type formed\">Nitrate<\/td>\n                <td data-label=\"Example salt\">Mg(NO<sub>3<\/sub>)<sub>2<\/sub><\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n        <div class=\"ols-key-box\"><p><strong>Exam focus:<\/strong> do not just memorise the word equation. Use the ions present to write a correct salt formula, then balance the full equation.<\/p><\/div>\n      <\/article>\n\n      <div class=\"ols-zoom-card\">\n        <div class=\"ols-zoom-card-image\">\n          <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Chemical-reactions-of-acids-infographic.webp\" alt=\"Summary infographic showing typical chemical reactions of acids\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>Use the acid to identify the negative ion in the salt, then use the reacting metal, base or carbonate to identify the positive ion.<\/p>\n        <\/div>\n      <\/div>\n\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">7<\/div><h2>How to Write Ionic Equations for Acid Reactions<\/h2><\/div>\n        <p>To write an ionic equation, show aqueous ionic substances as their ions, then remove any ions that appear unchanged on both sides. These unchanged ions are called <strong>spectator ions<\/strong>.<\/p>\n        <ol>\n          <li>Start from a correct balanced full equation.<\/li>\n          <li>Split aqueous acids, soluble salts and soluble alkalis into ions.<\/li>\n          <li>Keep solids, liquids, gases and covalent substances together.<\/li>\n          <li>Cancel spectator ions that are unchanged on both sides.<\/li>\n          <li>Check that atoms and charges are balanced.<\/li>\n        <\/ol>\n        <div class=\"ols-definition-box\"><p><strong>Spectator ion:<\/strong> an ion present in the reaction mixture that does not change during the chemical reaction.<\/p><\/div>\n        <div class=\"ols-key-box\"><p><strong>Useful summary:<\/strong> acid-metal reactions often reduce to metal + H<sup>+<\/sup> ions, while acid-carbonate reactions often reduce to carbonate ions + H<sup>+<\/sup> ions.<\/p><\/div>\n      <\/article>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">8<\/div><h2>Common Exam Points<\/h2><\/div>\n        <ul>\n          <li>A salt forms when the H<sup>+<\/sup> ion of an acid is replaced by a metal ion or ammonium ion.<\/li>\n          <li>Bases neutralise acids. Alkalis are soluble bases that release OH<sup>&#8211;<\/sup> ions in water.<\/li>\n          <li>Acid + metal produces a salt and hydrogen gas.<\/li>\n          <li>Acid + metal carbonate produces a salt, carbon dioxide and water.<\/li>\n          <li>Acid + metal hydroxide produces a salt and water.<\/li>\n          <li>Hydrochloric acid forms chlorides, sulfuric acid forms sulfates and nitric acid forms nitrates.<\/li>\n          <li>Fizzing in acid-metal reactions is usually hydrogen gas.<\/li>\n          <li>Fizzing in acid-carbonate reactions is carbon dioxide gas.<\/li>\n          <li>When writing ionic equations, remove spectator ions that appear unchanged on both sides.<\/li>\n          <li>Always check both atom balance and charge balance in an ionic equation.<\/li>\n        <\/ul>\n      <\/article>\n\n      <section class=\"ols-h5p-card\">\n        <h2>Check Your Understanding<\/h2>\n        <p>Use these short activities to practise identifying acid reaction patterns and recognising the ionic particles that actually change.<\/p>\n        <div class=\"ols-h5p-grid\">\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-288\" class=\"h5p-iframe\" data-content-id=\"288\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Ionic Equations: Precipitation and Displacement\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-289\" class=\"h5p-iframe\" data-content-id=\"289\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Full and Ionic Equations\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-327\" class=\"h5p-iframe\" data-content-id=\"327\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Identifying the reaction that is not a neutralisation reaction\"><\/iframe><\/div><\/div>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-quicksnap-card\">\n        <h2>QuickSnap<\/h2>\n        <p>This text summary condenses the page into the essential exam ideas.<\/p>\n        <ul class=\"ols-quicksnap-list\">\n          <li><strong>Acids supply H<sup>+<\/sup> ions:<\/strong> these ions drive typical acid reactions in aqueous solution.<\/li>\n          <li><strong>Neutralisation:<\/strong> H<sup>+<\/sup>(aq) reacts with OH<sup>&#8211;<\/sup>(aq) to form H<sub>2<\/sub>O(l).<\/li>\n          <li><strong>Metals:<\/strong> acid + metal \u2192 salt + hydrogen.<\/li>\n          <li><strong>Carbonates:<\/strong> acid + carbonate \u2192 salt + carbon dioxide + water.<\/li>\n          <li><strong>Salt names:<\/strong> HCl forms chlorides, H<sub>2<\/sub>SO<sub>4<\/sub> forms sulfates and HNO<sub>3<\/sub> forms nitrates.<\/li>\n          <li><strong>Ionic equations:<\/strong> split aqueous ionic substances into ions, then cancel spectator ions.<\/li>\n        <\/ul>\n      <\/section>\n\n\n      <div class=\"ols-image-lightbox\" id=\"olsImageLightboxTypicalAcids001\" aria-hidden=\"true\" role=\"dialog\" aria-modal=\"true\" aria-label=\"Expanded revision image\">\n        <div class=\"ols-image-lightbox-inner\">\n          <button class=\"ols-image-lightbox-close\" type=\"button\" aria-label=\"Close enlarged image\">\u00d7<\/button>\n          <img decoding=\"async\" class=\"ols-image-lightbox-img\" src=\"\" alt=\"\">\n        <\/div>\n      <\/div>\n\n      <script>\n        (function(){\n          var page = document.querySelector(\".ols-typical-reactions-of-acids-page\");\n          if (!page) {\n            return;\n          }\n\n          var lightbox = page.querySelector(\"#olsImageLightboxTypicalAcids001\");\n          if (!lightbox) {\n            return;\n          }\n\n          var lightboxImage = lightbox.querySelector(\".ols-image-lightbox-img\");\n          var closeButton = 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.ols-course-button {\r\n        width: 100%;\r\n      }\r\n    }\r\n  <\/style>\r\n\r\n  <div class=\"ols-course-cta-card\">\r\n\r\n    <div class=\"ols-course-cta-top\">\r\n\r\n      <a class=\"ols-course-cta-image-link\" href=\"https:\/\/onlinelearningsystem.net\/xyz\/shop\" aria-label=\"Open the Edexcel A Level Chemistry Topic 5 Formulae, Equations and Amounts of Substance course page\">\r\n\r\n        <div class=\"ols-course-cta-image\">\r\n          <img decoding=\"async\"\r\n            src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Edexcel-Topic-5-Formulae-Equations-and-Amounts-of-Substance.jpg\"\r\n            alt=\"Edexcel A Level Chemistry Topic 5 Formulae, Equations and Amounts of Substance course banner\"\r\n          >\r\n        <\/div>\r\n\r\n      <\/a>\r\n\r\n      <div class=\"ols-course-cta-content\">\r\n\r\n        <div class=\"ols-course-cta-header-row\">\r\n\r\n          <div class=\"ols-course-cta-kicker\">\r\n            Complete Topic 5 Formulae, Equations & Amounts of Substance Course\r\n          <\/div>\r\n\r\n          <a class=\"ols-course-button ols-course-button-top\" href=\"https:\/\/onlinelearningsystem.net\/xyz\/shop\">\r\n            View Course\r\n          <\/a>\r\n\r\n        <\/div>\r\n\r\n        <h2>\r\n          Master Formulae, Equations and Amounts of Substance for Edexcel A Level Chemistry\r\n        <\/h2>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ols-course-cta-intro-stats\">\r\n\r\n      <p class=\"ols-course-cta-intro\">\r\n        Continue from these free revision notes into the full Topic 5 Formulae, Equations and Amounts of Substance course, with guided video teaching, diagnostic MCQ practice, teacher-marked short-answer questions and a specification assignment with a personalised progress report.\r\n      <\/p>\r\n\r\n      <div class=\"ols-course-cta-stats\">\r\n\r\n        <div class=\"ols-course-stat\">\r\n          <span>Guided learning<\/span>\r\n          <strong>Complete Topic 5<\/strong>\r\n        <\/div>\r\n\r\n        <div class=\"ols-course-stat\">\r\n          <span>Video lessons<\/span>\r\n          <strong>Full virtual lesson<\/strong>\r\n        <\/div>\r\n\r\n        <div class=\"ols-course-stat\">\r\n          <span>MCQ practice<\/span>\r\n          <strong>123 marks<\/strong>\r\n        <\/div>\r\n\r\n        <div class=\"ols-course-stat\">\r\n          <span>SAQ practice<\/span>\r\n          <strong>up to 145 marks<\/strong>\r\n        <\/div>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ols-course-cta-features\">\r\n\r\n      <div class=\"ols-course-feature\">\r\n        <h3>Guided video teaching<\/h3>\r\n        <p>\r\n          Learn formulae, balanced equations, ionic equations, relative masses, mole calculations, empirical formulae, reacting masses, gas volumes, percentage yield and atom economy through structured video lessons with worked examples and walkthroughs.\r\n        <\/p>\r\n      <\/div>\r\n\r\n      <div class=\"ols-course-feature\">\r\n        <h3>Instant MCQ feedback<\/h3>\r\n        <p>\r\n          Auto-marked MCQ quizzes provide immediate diagnostic feedback for every answer choice.\r\n        <\/p>\r\n      <\/div>\r\n\r\n      <div class=\"ols-course-feature\">\r\n        <h3>Teacher-marked SAQs<\/h3>\r\n        <p>\r\n          Submit written exam responses and receive chemistry specialist feedback with improvement guidance.\r\n        <\/p>\r\n      <\/div>\r\n\r\n      <div class=\"ols-course-feature\">\r\n        <h3>Progress tracking<\/h3>\r\n        <p>\r\n          Identify strengths and weaknesses across formulae, equations, mole calculations, concentration, empirical formulae, percentage yield, atom economy and test-tube reactions with targeted reporting.\r\n        <\/p>\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ols-course-animation-wrap\">\r\n\r\n      <h3 class=\"ols-course-animation-title\">\r\n        See how the course works\r\n      <\/h3>\r\n\r\n      <div class=\"ols-animation-frame-shell\">\r\n        <iframe\r\n          id=\"olsCourseAnimationFrame005\"\r\n          title=\"OLS course preview animation\"\r\n          loading=\"lazy\"\r\n          referrerpolicy=\"no-referrer\">\r\n        <\/iframe>\r\n\r\n        <button\r\n          class=\"ols-animation-start-overlay\"\r\n          id=\"olsCourseAnimationStart005\"\r\n          type=\"button\"\r\n          aria-label=\"Play OLS course preview animation\">\r\n          <span class=\"ols-animation-start-content\">\r\n            <span class=\"ols-animation-play-circle\" aria-hidden=\"true\">\r\n              <span class=\"ols-animation-play-icon\"><\/span>\r\n            <\/span>\r\n            <span class=\"ols-animation-start-text\">\r\n              Play course preview animation\r\n            <\/span>\r\n          <\/span>\r\n        <\/button>\r\n\r\n        <button\r\n          class=\"ols-animation-pause-button\"\r\n          id=\"olsCourseAnimationPause005\"\r\n          type=\"button\"\r\n          aria-label=\"Pause course preview animation\">\r\n          Pause\r\n        <\/button>\r\n      <\/div>\r\n\r\n      <p class=\"ols-course-video-status\">\r\n        Click play to start the course preview animation.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ols-course-cta-bottom\">\r\n\r\n      <a class=\"ols-course-button\" href=\"https:\/\/onlinelearningsystem.net\/xyz\/shop\">\r\n        View Formulae, Equations & Amounts of Substance Topic 5 Course\r\n      <\/a>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n  <template id=\"olsCourseAnimationTemplate005\">\r\n<!DOCTYPE html>\r\n<html lang=\"en\">\r\n<head>\r\n<meta charset=\"UTF-8\">\r\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">\r\n<title>OLS Combined Promo Animation<\/title>\r\n\r\n<style>\r\n*{box-sizing:border-box;}\r\n\r\nhtml.ols-animation-paused *,\r\nhtml.ols-animation-paused *::before,\r\nhtml.ols-animation-paused *::after{\r\n  animation-play-state:paused!important;\r\n}\r\n\r\n:root{\r\n  --ols-video-screen-w:1180;\r\n  --ols-video-screen-h:664;\r\n  --ols-video-screen-scale:1;\r\n  --ols-mcq-screen-w:1360;\r\n  --ols-mcq-screen-h:1130;\r\n  --ols-mcq-screen-scale:1;\r\n  --ols-saq-screen-w:1360;\r\n  --ols-saq-screen-h:965;\r\n  --ols-saq-screen-scale:1;\r\n}\r\n\r\nhtml,\r\nbody{\r\n  width:100%;\r\n  height:100%;\r\n}\r\n\r\nbody{\r\n  margin:0;\r\n  overflow:hidden;\r\n  font-family:Poppins,Arial,sans-serif;\r\n  background:#e9efff;\r\n}\r\n\r\n.ols-combined-stage{\r\n  position:relative;\r\n  width:100vw;\r\n  height:100vh;\r\n  overflow:hidden;\r\n  background:\r\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\r\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\r\n}\r\n\r\n.ols-scene{\r\n  position:absolute;\r\n  inset:0;\r\n  width:100vw;\r\n  height:100vh;\r\n  opacity:0;\r\n  visibility:hidden;\r\n  pointer-events:none;\r\n}\r\n\r\n.ols-scene.active{\r\n  opacity:1;\r\n  visibility:visible;\r\n  pointer-events:auto;\r\n}\r\n\r\n.ols-scene.fade-out{\r\n  animation:olsSceneFadeOut 0.85s ease forwards;\r\n}\r\n\r\n@keyframes olsSceneFadeOut{\r\n  to{\r\n    opacity:0;\r\n    visibility:hidden;\r\n  }\r\n}\r\n\r\n.ols-title-cursor{\r\n  display:inline-block;\r\n  width:5px;\r\n  height:0.85em;\r\n  background:#1C244B;\r\n  margin-left:8px;\r\n  transform:translateY(8px);\r\n  animation:olsBlink 0.8s infinite;\r\n}\r\n\r\n.cursor{\r\n  display:inline-block;\r\n  width:3px;\r\n  height:28px;\r\n  background:#1c244b;\r\n  margin-left:3px;\r\n  transform:translateY(5px);\r\n  animation:olsBlink 0.8s infinite;\r\n}\r\n\r\n@keyframes olsBlink{\r\n  0%,45%{opacity:1;}\r\n  46%,100%{opacity:0;}\r\n}\r\n\r\n.ols-video-stage,\r\n.ols-mcq-stage,\r\n.ols-saq-stage{\r\n  width:100vw;\r\n  height:100vh;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n  padding:0;\r\n  overflow:hidden;\r\n  background:\r\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\r\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\r\n}\r\n\r\n.ols-video-title-screen,\r\n.ols-mcq-intro-screen,\r\n.ols-saq-intro{\r\n  position:absolute;\r\n  inset:0;\r\n  z-index:50;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n  background:\r\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\r\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\r\n  opacity:1;\r\n  visibility:visible;\r\n  pointer-events:none;\r\n}\r\n\r\n.ols-video-title-screen.hide{animation:olsVideoTitleFadeOut 0.85s ease forwards;}\r\n.ols-mcq-intro-screen.hide{animation:olsMcqIntroFadeOut 0.85s ease forwards;}\r\n.ols-saq-intro.hide{animation:olsSaqIntroFadeOut 0.85s ease forwards;}\r\n\r\n@keyframes olsVideoTitleFadeOut{to{opacity:0;visibility:hidden;}}\r\n@keyframes olsMcqIntroFadeOut{to{opacity:0;visibility:hidden;}}\r\n@keyframes olsSaqIntroFadeOut{to{opacity:0;visibility:hidden;}}\r\n\r\n.ols-video-title-wrap,\r\n.ols-mcq-intro-title-wrap,\r\n.ols-saq-intro-title-wrap{\r\n  max-width:1250px;\r\n  padding:0 34px;\r\n  text-align:center;\r\n}\r\n\r\n.ols-video-title,\r\n.ols-mcq-intro-title,\r\n.ols-saq-intro-title{\r\n  margin:0;\r\n  font-family:Poppins,Arial,sans-serif;\r\n  font-size:clamp(52px,8vw,124px);\r\n  font-weight:600;\r\n  line-height:1.08;\r\n  color:#1C244B;\r\n  text-shadow:-9px 0 9px rgba(28,36,75,0.16);\r\n  letter-spacing:-0.045em;\r\n}\r\n\r\n#videoTitleText,\r\n#mcqIntroTitleText,\r\n#saqIntroTitleText{\r\n  white-space:pre-wrap;\r\n}\r\n\r\n.ols-video-scene{\r\n  width:100%;\r\n  height:100%;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n  opacity:0;\r\n  visibility:hidden;\r\n}\r\n\r\n.ols-video-scene.show{\r\n  visibility:visible;\r\n  animation:olsVideoSceneIn 1s ease forwards;\r\n}\r\n\r\n@keyframes olsVideoSceneIn{to{opacity:1;}}\r\n\r\n.ols-video-scale-wrap{\r\n  width:calc(var(--ols-video-screen-w) * 1px);\r\n  height:calc(var(--ols-video-screen-h) * 1px);\r\n  transform:scale(var(--ols-video-screen-scale));\r\n  transform-origin:center center;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n}\r\n\r\n.ols-video-card{\r\n  width:1180px;\r\n  height:664px;\r\n  border-radius:28px;\r\n  overflow:hidden;\r\n  background:#1C244B;\r\n  box-shadow:0 28px 80px rgba(28,36,75,0.28);\r\n  transform:translateY(24px) scale(0.96);\r\n  opacity:0;\r\n}\r\n\r\n.ols-video-scene.show .ols-video-card{\r\n  animation:olsVideoCardIn 1s cubic-bezier(.18,.89,.32,1.12) forwards;\r\n  animation-delay:0.2s;\r\n}\r\n\r\n@keyframes olsVideoCardIn{\r\n  to{\r\n    transform:translateY(0) scale(1);\r\n    opacity:1;\r\n  }\r\n}\r\n\r\n.ols-video-card video{\r\n  display:block;\r\n  width:100%;\r\n  height:100%;\r\n  aspect-ratio:16 \/ 9;\r\n  object-fit:cover;\r\n  border:0;\r\n}\r\n\r\n.ols-mcq-scale-wrap,\r\n.ols-saq-scale-wrap{\r\n  width:calc(var(--ols-mcq-screen-w) * 1px);\r\n  height:calc(var(--ols-mcq-screen-h) * 1px);\r\n  transform:scale(var(--ols-mcq-screen-scale));\r\n  transform-origin:center center;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:flex-start;\r\n}\r\n\r\n.ols-saq-scale-wrap{\r\n  width:calc(var(--ols-saq-screen-w) * 1px);\r\n  height:calc(var(--ols-saq-screen-h) * 1px);\r\n  transform:scale(var(--ols-saq-screen-scale));\r\n}\r\n\r\n.ols-mcq-screen{\r\n  width:1360px;\r\n  height:1130px;\r\n  border-radius:22px;\r\n  overflow:hidden;\r\n  background:#eaf0ff;\r\n  box-shadow:0 26px 70px rgba(28,36,75,0.22);\r\n  opacity:0;\r\n  transform:translateY(24px) scale(0.96);\r\n}\r\n\r\n.ols-mcq-screen.show{\r\n  animation:olsMcqScreenEnter 1s ease forwards;\r\n}\r\n\r\n@keyframes olsMcqScreenEnter{\r\n  from{opacity:0;transform:translateY(24px) scale(0.96);}\r\n  to{opacity:1;transform:translateY(0) scale(1);}\r\n}\r\n\r\n.mcq-question-area{\r\n  background:#eaf0ff;\r\n  padding:28px 30px 30px;\r\n  position:relative;\r\n  height:610px;\r\n}\r\n\r\n.mcq-question-lead{\r\n  margin:0 0 14px;\r\n  font-size:24px;\r\n  line-height:1.35;\r\n  color:#111827;\r\n}\r\n\r\n.mcq-data-table{\r\n  border-collapse:collapse;\r\n  width:500px;\r\n  margin-bottom:8px;\r\n  font-size:21px;\r\n  color:#111827;\r\n}\r\n\r\n.mcq-data-table th,\r\n.mcq-data-table td{\r\n  border:1.5px solid #c9ced8;\r\n  padding:12px 18px;\r\n  text-align:center;\r\n}\r\n\r\n.mcq-data-table th{\r\n  background:#f2f2f2;\r\n  font-weight:700;\r\n}\r\n\r\n.mcq-data-table td{\r\n  background:#eaf0ff;\r\n}\r\n\r\n.mcq-question-main{\r\n  margin:6px 0 28px;\r\n  font-size:24px;\r\n  line-height:1.35;\r\n  color:#111827;\r\n}\r\n\r\n.mcq-options-wrap{\r\n  display:flex;\r\n  flex-direction:column;\r\n  gap:17px;\r\n  max-width:1200px;\r\n}\r\n\r\n.mcq-option-row{\r\n  display:flex;\r\n  align-items:center;\r\n  min-height:34px;\r\n  position:relative;\r\n}\r\n\r\n.mcq-radio{\r\n  width:28px;\r\n  height:28px;\r\n  border-radius:50%;\r\n  border:2px solid #6b7280;\r\n  margin-right:16px;\r\n  background:transparent;\r\n  position:relative;\r\n  flex:0 0 auto;\r\n}\r\n\r\n.mcq-radio::after{\r\n  content:\"\";\r\n  position:absolute;\r\n  inset:5px;\r\n  border-radius:50%;\r\n  background:#6b7280;\r\n  opacity:0;\r\n  transform:scale(0.4);\r\n  transition:opacity 0.25s ease,transform 0.25s ease;\r\n}\r\n\r\n.mcq-option-row.selected .mcq-radio::after{\r\n  opacity:1;\r\n  transform:scale(1);\r\n}\r\n\r\n.mcq-radio-ripple{\r\n  position:absolute;\r\n  left:14px;\r\n  top:50%;\r\n  width:28px;\r\n  height:28px;\r\n  border-radius:50%;\r\n  border:2px solid rgba(28,36,75,0.28);\r\n  transform:translate(-50%,-50%) scale(1);\r\n  opacity:0;\r\n  pointer-events:none;\r\n}\r\n\r\n.mcq-option-row.clicking .mcq-radio-ripple{\r\n  animation:mcqRipple 0.75s ease forwards;\r\n}\r\n\r\n@keyframes mcqRipple{\r\n  0%{opacity:0.65;transform:translate(-50%,-50%) scale(1);}\r\n  100%{opacity:0;transform:translate(-50%,-50%) scale(2.5);}\r\n}\r\n\r\n.mcq-option-label{\r\n  font-size:23px;\r\n  color:#111827;\r\n}\r\n\r\n.mcq-specific-feedback{\r\n  display:inline-flex;\r\n  align-items:center;\r\n  margin-left:18px;\r\n  min-height:38px;\r\n  opacity:0;\r\n  transform:translateX(-8px);\r\n}\r\n\r\n.mcq-specific-feedback.show{\r\n  opacity:1;\r\n  transform:translateX(0);\r\n  transition:opacity 0.35s ease,transform 0.35s ease;\r\n}\r\n\r\n.mcq-cross-icon{\r\n  width:26px;\r\n  height:26px;\r\n  border-radius:50%;\r\n  border:2px solid #d83255;\r\n  color:#d83255;\r\n  display:inline-flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n  font-size:18px;\r\n  font-weight:700;\r\n  margin-right:12px;\r\n  opacity:0;\r\n  transform:scale(0.4);\r\n}\r\n\r\n.mcq-cross-icon.show{\r\n  animation:mcqCrossPop 0.35s ease forwards;\r\n}\r\n\r\n@keyframes mcqCrossPop{\r\n  70%{opacity:1;transform:scale(1.18);}\r\n  100%{opacity:1;transform:scale(1);}\r\n}\r\n\r\n.mcq-specific-feedback-text{\r\n  display:inline-block;\r\n  background:#fff4b8;\r\n  color:#111827;\r\n  padding:8px 16px;\r\n  font-size:22px;\r\n  line-height:1.35;\r\n  min-width:850px;\r\n  min-height:44px;\r\n}\r\n\r\n.mcq-submit-button{\r\n  position:absolute;\r\n  right:34px;\r\n  bottom:30px;\r\n  border:0;\r\n  border-radius:999px;\r\n  background:#1C244B;\r\n  color:#ffffff;\r\n  padding:14px 28px;\r\n  font-size:18px;\r\n  font-weight:600;\r\n  box-shadow:0 14px 32px rgba(28,36,75,0.25);\r\n  cursor:default;\r\n  transition:transform 0.2s ease,box-shadow 0.2s ease,background 0.2s ease;\r\n}\r\n\r\n.mcq-submit-button.clicked{\r\n  transform:translateY(2px) scale(0.97);\r\n  background:#26315f;\r\n  box-shadow:0 7px 18px rgba(28,36,75,0.22);\r\n}\r\n\r\n.mcq-general-feedback{\r\n  height:520px;\r\n  background:#fff3c9;\r\n  color:#8a6a00;\r\n  padding:26px 30px 28px;\r\n  font-size:23px;\r\n  line-height:1.34;\r\n  opacity:0;\r\n  transform:translateY(20px);\r\n  transition:opacity 0.7s ease,transform 0.7s ease;\r\n  overflow:hidden;\r\n}\r\n\r\n.mcq-general-feedback.show{\r\n  opacity:1;\r\n  transform:translateY(0);\r\n}\r\n\r\n#mcqGeneralText{\r\n  white-space:pre-wrap;\r\n}\r\n\r\n.mcq-specific-cursor{background:#111827;}\r\n.mcq-general-cursor{background:#8a6a00;}\r\n\r\n.ols-saq-screen{\r\n  width:1360px;\r\n  height:965px;\r\n  border-radius:22px;\r\n  overflow:hidden;\r\n  background:#eaf0ff;\r\n  box-shadow:0 26px 70px rgba(28,36,75,0.22);\r\n  opacity:0;\r\n  transform:translateY(24px) scale(0.96);\r\n}\r\n\r\n.ols-saq-screen.show{\r\n  animation:olsSaqScreenEnter 1s ease forwards;\r\n}\r\n\r\n@keyframes olsSaqScreenEnter{\r\n  from{opacity:0;transform:translateY(24px) scale(0.96);}\r\n  to{opacity:1;transform:translateY(0) scale(1);}\r\n}\r\n\r\n.saq-question-area{\r\n  height:335px;\r\n  background:#eaf0ff;\r\n  padding:30px 40px 32px;\r\n}\r\n\r\n.saq-question-text{\r\n  font-size:25px;\r\n  line-height:1.42;\r\n  color:#111827;\r\n  margin-bottom:22px;\r\n}\r\n\r\n.saq-student-box{\r\n  height:195px;\r\n  background:#f3f4f6;\r\n  border:2px solid #cfd6e3;\r\n  border-radius:8px;\r\n  padding:23px 26px;\r\n  font-size:24px;\r\n  line-height:1.55;\r\n  color:#4b5563;\r\n  position:relative;\r\n  overflow:hidden;\r\n}\r\n\r\n.saq-teacher-feedback{\r\n  height:630px;\r\n  background:#dff3e6;\r\n  color:#075f3b;\r\n  padding:28px 40px 30px;\r\n  font-size:23px;\r\n  line-height:1.47;\r\n  opacity:0;\r\n  transform:translateY(20px);\r\n  transition:opacity 0.7s ease,transform 0.7s ease;\r\n  overflow:hidden;\r\n}\r\n\r\n.saq-teacher-feedback.show{\r\n  opacity:1;\r\n  transform:translateY(0);\r\n}\r\n\r\n#saqTeacherText{\r\n  white-space:pre-wrap;\r\n}\r\n\r\n.saq-teacher-cursor{\r\n  background:#075f3b;\r\n}\r\n\r\n@media(max-width:900px){\r\n  .ols-video-title,\r\n  .ols-mcq-intro-title,\r\n  .ols-saq-intro-title{\r\n    font-size:clamp(42px,11vw,78px);\r\n    line-height:1.12;\r\n  }\r\n\r\n  .ols-title-cursor{\r\n    width:4px;\r\n    margin-left:6px;\r\n  }\r\n\r\n  .ols-video-card{\r\n    border-radius:20px;\r\n  }\r\n}\r\n<\/style>\r\n<\/head>\r\n\r\n<body>\r\n<div class=\"ols-combined-stage\">\r\n\r\n  <section id=\"sceneVideo\" class=\"ols-scene active\">\r\n    <div class=\"ols-video-stage\">\r\n      <div id=\"videoTitleScreen\" class=\"ols-video-title-screen\">\r\n        <div class=\"ols-video-title-wrap\">\r\n          <h1 class=\"ols-video-title\">\r\n            <span id=\"videoTitleText\"><\/span><span id=\"videoTitleCursor\" class=\"ols-title-cursor\"><\/span>\r\n          <\/h1>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <section id=\"videoScene\" class=\"ols-video-scene\">\r\n        <div class=\"ols-video-scale-wrap\">\r\n          <div class=\"ols-video-card\">\r\n            <video\r\n              id=\"lessonVideo\"\r\n              src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Virtual-Lesson.mp4\"\r\n              muted\r\n              playsinline\r\n              preload=\"auto\">\r\n            <\/video>\r\n          <\/div>\r\n        <\/div>\r\n      <\/section>\r\n    <\/div>\r\n  <\/section>\r\n\r\n  <section id=\"sceneMcq\" class=\"ols-scene\">\r\n    <div class=\"ols-mcq-stage\">\r\n      <div id=\"mcqIntroScreen\" class=\"ols-mcq-intro-screen\">\r\n        <div class=\"ols-mcq-intro-title-wrap\">\r\n          <h1 class=\"ols-mcq-intro-title\">\r\n            <span id=\"mcqIntroTitleText\"><\/span><span id=\"mcqIntroTitleCursor\" class=\"ols-title-cursor\"><\/span>\r\n          <\/h1>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ols-mcq-scale-wrap\">\r\n        <main id=\"mcqScreen\" class=\"ols-mcq-screen\">\r\n          <section class=\"mcq-question-area\">\r\n            <p class=\"mcq-question-lead\">A compound contains carbon, hydrogen and oxygen only. Its percentage composition by mass is shown.<\/p>\r\n\r\n            <table class=\"mcq-data-table\">\r\n              <thead>\r\n                <tr>\r\n                  <th>Element<\/th>\r\n                  <th>Percentage by mass<\/th>\r\n                <\/tr>\r\n              <\/thead>\r\n              <tbody>\r\n                <tr><td>C<\/td><td>40.0%<\/td><\/tr>\r\n                <tr><td>H<\/td><td>6.7%<\/td><\/tr>\r\n                <tr><td>O<\/td><td>53.3%<\/td><\/tr>\r\n              <\/tbody>\r\n            <\/table>\r\n\r\n            <p class=\"mcq-question-main\">What is the empirical formula of the compound?<\/p>\r\n\r\n            <div class=\"mcq-options-wrap\">\r\n              <div id=\"mcqWrongOption\" class=\"mcq-option-row\">\r\n                <span class=\"mcq-radio\"><\/span>\r\n                <span class=\"mcq-radio-ripple\"><\/span>\r\n                <span class=\"mcq-option-label\">C<sub>2<\/sub>H<sub>4<\/sub>O<sub>2<\/sub><\/span>\r\n\r\n                <span id=\"mcqSpecificFeedback\" class=\"mcq-specific-feedback\">\r\n                  <span id=\"mcqCrossIcon\" class=\"mcq-cross-icon\">\u00d7<\/span>\r\n                  <span class=\"mcq-specific-feedback-text\">\r\n                    <span id=\"mcqSpecificText\"><\/span><span id=\"mcqSpecificCursor\" class=\"cursor mcq-specific-cursor\" style=\"display:none;\"><\/span>\r\n                  <\/span>\r\n                <\/span>\r\n              <\/div>\r\n\r\n              <div class=\"mcq-option-row\"><span class=\"mcq-radio\"><\/span><span class=\"mcq-radio-ripple\"><\/span><span class=\"mcq-option-label\">CH<sub>2<\/sub>O<\/span><\/div>\r\n              <div class=\"mcq-option-row\"><span class=\"mcq-radio\"><\/span><span class=\"mcq-radio-ripple\"><\/span><span class=\"mcq-option-label\">CHO<\/span><\/div>\r\n              <div class=\"mcq-option-row\"><span class=\"mcq-radio\"><\/span><span class=\"mcq-radio-ripple\"><\/span><span class=\"mcq-option-label\">CH<sub>4<\/sub>O<\/span><\/div>\r\n            <\/div>\r\n\r\n            <button id=\"mcqSubmitButton\" class=\"mcq-submit-button\">Submit answer<\/button>\r\n          <\/section>\r\n\r\n          <section id=\"mcqGeneralFeedback\" class=\"mcq-general-feedback\">\r\n            <span id=\"mcqGeneralText\"><\/span><span id=\"mcqGeneralCursor\" class=\"cursor mcq-general-cursor\" style=\"display:none;\"><\/span>\r\n          <\/section>\r\n        <\/main>\r\n      <\/div>\r\n    <\/div>\r\n  <\/section>\r\n\r\n  <section id=\"sceneSaq\" class=\"ols-scene\">\r\n    <div class=\"ols-saq-stage\">\r\n      <div id=\"saqIntro\" class=\"ols-saq-intro\">\r\n        <div class=\"ols-saq-intro-title-wrap\">\r\n          <h1 class=\"ols-saq-intro-title\">\r\n            <span id=\"saqIntroTitleText\"><\/span><span id=\"saqIntroTitleCursor\" class=\"ols-title-cursor\"><\/span>\r\n          <\/h1>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ols-saq-scale-wrap\">\r\n        <main id=\"saqScreen\" class=\"ols-saq-screen\">\r\n          <section class=\"saq-question-area\">\r\n            <div class=\"saq-question-text\">\r\n              <strong>(ii)<\/strong>&nbsp;&nbsp; A student reacts magnesium with hydrochloric acid and collects hydrogen gas.<br>\r\n              Explain how the volume of hydrogen can be used to calculate the amount of magnesium that reacted.\r\n            <\/div>\r\n\r\n            <div class=\"saq-student-box\">\r\n              <span id=\"saqStudentText\"><\/span><span id=\"saqStudentCursor\" class=\"cursor\"><\/span>\r\n            <\/div>\r\n          <\/section>\r\n\r\n          <section id=\"saqTeacherFeedback\" class=\"saq-teacher-feedback\">\r\n            <span id=\"saqTeacherText\"><\/span><span id=\"saqTeacherCursor\" class=\"cursor saq-teacher-cursor\" style=\"display:none;\"><\/span>\r\n          <\/section>\r\n        <\/main>\r\n      <\/div>\r\n    <\/div>\r\n  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The mole ratio between magnesium and hydrogen is 1 : 1, so the amount of hydrogen produced is equal to the amount of magnesium that reacted.\\n\\n\"+\r\n\"The volume of hydrogen can be converted into moles using the molar volume of gas, or pV = nRT if pressure and temperature data are supplied. Once the moles of H\u2082 are known, the 1 : 1 ratio gives the moles of Mg. 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For example, magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>What is formed when an acid reacts with a metal carbonate?<\/h3>\n            <p>An acid reacts with a metal carbonate to form a salt, carbon dioxide and water. The carbon dioxide causes fizzing and can be tested using limewater.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>What is the difference between a base and an alkali?<\/h3>\n            <p>A base neutralises an acid. An alkali is a soluble base that releases OH<sup>&#8211;<\/sup> ions in aqueous solution.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>How do I know whether a salt is a chloride, sulfate or nitrate?<\/h3>\n            <p>The acid used determines the negative ion in the salt. Hydrochloric acid forms chlorides, sulfuric acid forms sulfates and nitric acid forms nitrates.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Why do different acid reactions sometimes have the same ionic equation?<\/h3>\n            <p>Different full equations can contain spectator ions. When these unchanged ions are removed, the net ionic equation may be the same because the same reacting particles are involved.<\/p>\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-related-card\">\n        <h2>Related Topics<\/h2>\n        <p>Use these pages next to strengthen the surrounding skills needed for equations, ionic equations and quantitative chemistry.<\/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\/topic-5-formulae-equations-and-amounts-of-substance\/atoms-elements-and-molecules\/\">Atoms, Elements and Molecules<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/writing-chemical-equations\/\">Writing Chemical Equations<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/\">Displacement Reactions<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/ionic-and-full-equations\/\">Ionic Equations<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/mole-calculations\/\">Mole Calculations<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/ionic-bonding\/\">Ionic Bonding<\/a>\n        <\/div>\n      <\/section>\n\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\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\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/typical-reactions-of-acids\/#webpage\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/equations-and-reaction-types\/typical-reactions-of-acids\/\",\n            \"name\": \"Typical Reactions of Acids - Edexcel A Level Chemistry Revision Notes\",\n            \"description\": \"Revision notes covering typical reactions of acids, including neutralisation, acid-metal reactions, acid-carbonate 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