{"id":4753,"date":"2026-06-02T07:46:56","date_gmt":"2026-06-02T06:46:56","guid":{"rendered":"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\/"},"modified":"2026-06-28T05:51:00","modified_gmt":"2026-06-28T04:51:00","slug":"molar-volume-calculations","status":"publish","type":"page","link":"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\/","title":{"rendered":"Molar Volume Calculations"},"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-9CH0-T5-MOLAR-VOLUME-CALCULATIONS-REVISION-PAGE-2026\n\nPage:\nMolar Volume Calculations\nEdexcel A Level Chemistry\nPaper 1 and Paper 2\nTopic 5: Formulae, Equations and Amounts of Substance\n9CH0\/01 and 9CH0\/02\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-molar-volume-page\" data-owner=\"Online Learning System\" data-copyright=\"\u00a9 Online Learning System. 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{\n      .ols-image-lightbox {\n        padding: 16px;\n      }\n\n      .ols-image-lightbox-inner {\n        width: 100%;\n        max-height: 88vh;\n      }\n\n      .ols-image-lightbox-img {\n        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: Molar Volume Calculations.\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\/calculations-with-solutions-and-gases\/\">Calculations with Solutions and Gases<\/a> \/\n        <span>Molar Volume Calculations<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Molar Volume Calculations<\/h1>\n        <p class=\"ols-page-intro\">A focused revision guide to molar volume calculations for Edexcel A Level Chemistry. This page covers Avogadro\u2019s law, molar gas volume at room temperature and pressure, reacting gas volume calculations and the ideal gas equation pV = nRT with full worked examples for Topic 5.<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Paper 1 and Paper 2<\/div>\n          <div class=\"ols-badge\">Topic 5: Formulae, Equations and Amounts of Substance<\/div>\n          <div class=\"ols-badge\">9CH0\/01 and 9CH0\/02<\/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      <!-- Card 1: Avogadro's Law -->\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">1<\/div><h2>Avogadro&#8217;s Law<\/h2><\/div>\n        <p><strong>Avogadro&#8217;s law<\/strong> states that equal volumes of any gases, measured under the same conditions of temperature and pressure, contain equal numbers of molecules (or atoms, if the gas is monatomic).<\/p>\n        <p>This means that for gases, the <strong>volume ratio<\/strong> in a reaction is the same as the <strong>mole ratio<\/strong>. If 1 mol of gas A occupies a certain volume under set conditions, then 2 mol of any other gas will occupy double that volume under the same conditions.<\/p>\n        <div class=\"ols-definition-box\">\n          <p><strong>Avogadro&#8217;s law:<\/strong> equal volumes of gases at the same temperature and pressure contain equal numbers of particles.<\/p>\n        <\/div>\n        <div class=\"ols-key-box\">\n          <p><strong>Why it matters:<\/strong> Avogadro&#8217;s law lets you treat gas volumes in a balanced equation as if they were moles, provided all the gases are measured under the same conditions.<\/p>\n        <\/div>\n      <\/article>\n\n      <!-- Image 1: Avogadro's law -->\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\/Avogadros-law-explained-visually.webp\" alt=\"Avogadro's law explained visually with equal gas volumes containing equal numbers of molecules\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>Different gases at the same temperature and pressure pack the same number of particles into the same volume, regardless of the size of the molecules.<\/p>\n        <\/div>\n      <\/div>\n\n      <!-- Card 2: The Molar Volume of a Gas -->\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">2<\/div><h2>The Molar Volume of a Gas<\/h2><\/div>\n        <p>The <strong>molar volume<\/strong> is the volume occupied by <strong>one mole of a gas<\/strong> at a specified temperature and pressure. Because Avogadro&#8217;s law applies, every gas has the same molar volume under the same conditions.<\/p>\n        <p>For Edexcel A Level Chemistry, you should know the two standard values:<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Conditions<\/th>\n                <th>Symbol<\/th>\n                <th>Molar volume<\/th>\n                <th>Equivalent in cm<sup>3<\/sup><\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Conditions\">Room temperature (25 \u00b0C) and pressure (1 atm)<\/td>\n                <td data-label=\"Symbol\">r.t.p.<\/td>\n                <td data-label=\"Molar volume\">24 dm<sup>3<\/sup> mol<sup>\u22121<\/sup><\/td>\n                <td data-label=\"Equivalent in cm\u00b3\">24 000 cm<sup>3<\/sup> mol<sup>\u22121<\/sup><\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Conditions\">Standard temperature (0 \u00b0C) and pressure (1 atm)<\/td>\n                <td data-label=\"Symbol\">s.t.p.<\/td>\n                <td data-label=\"Molar volume\">22.4 dm<sup>3<\/sup> mol<sup>\u22121<\/sup><\/td>\n                <td data-label=\"Equivalent in cm\u00b3\">22 400 cm<sup>3<\/sup> mol<sup>\u22121<\/sup><\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <p>The two key relationships you will use repeatedly are:<\/p>\n\n        <div class=\"ols-equation-box\">\n          <strong>Moles of gas<\/strong> = volume of gas (dm<sup>3<\/sup>) \u00f7 24\n        <\/div>\n        <div class=\"ols-equation-box\">\n          <strong>Volume of gas (dm<sup>3<\/sup>)<\/strong> = moles of gas \u00d7 24\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Unit check:<\/strong> if the volume is in cm<sup>3<\/sup>, divide by 24 000 instead of 24. Always check whether the question gives dm<sup>3<\/sup> or cm<sup>3<\/sup> before substituting.<\/p>\n        <\/div>\n      <\/article>\n\n      <!-- Image 2: Understanding molar volume -->\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\/Understanding-molar-volume-of-a-gas.webp\" alt=\"Understanding the molar volume of a gas at room temperature and pressure\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>One mole of any gas occupies the same volume under fixed conditions, which is what makes converting between moles and gas volumes so straightforward.<\/p>\n        <\/div>\n      <\/div>\n\n      <!-- Card 3: Calculating 1 Mole of Oxygen Example -->\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">3<\/div><h2>Worked Example: 1 Mole of Oxygen<\/h2><\/div>\n        <p>Calculate the volume occupied by <strong>1 mole of oxygen gas<\/strong> at r.t.p.<\/p>\n\n        <div class=\"ols-worked-example\">\n          <h3>Setting up the calculation<\/h3>\n          <p>At r.t.p., the molar volume of any gas is <strong>24 dm<sup>3<\/sup> mol<sup>\u22121<\/sup><\/strong>. This value applies to every gas, including oxygen, because of Avogadro&#8217;s law.<\/p>\n          <div class=\"ols-calc-row\">\n            <div class=\"ols-calc-cell\"><span>Moles of O<sub>2<\/sub><\/span>1 mol<\/div>\n            <div class=\"ols-calc-cell\"><span>Molar volume at r.t.p.<\/span>24 dm<sup>3<\/sup> mol<sup>\u22121<\/sup><\/div>\n            <div class=\"ols-calc-cell\"><span>Volume = moles \u00d7 24<\/span>1 \u00d7 24 = <strong>24 dm<sup>3<\/sup><\/strong><\/div>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Answer:<\/strong> 1 mol of O<sub>2<\/sub> occupies <strong>24 dm<sup>3<\/sup><\/strong> at r.t.p., which equals 24 000 cm<sup>3<\/sup>. The identity of the gas does not matter; nitrogen, hydrogen and carbon dioxide would all give the same volume under the same conditions.<\/p>\n        <\/div>\n      <\/article>\n\n      <!-- Image 3: Calculating molar volume of oxygen -->\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\/Calculating-molar-volume-of-oxygen.webp\" alt=\"Calculating the molar volume of oxygen gas at room temperature and pressure\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>Because the molar volume value already accounts for the conditions, the calculation reduces to a single multiplication by 24.<\/p>\n        <\/div>\n      <\/div>\n\n      <!-- Card 4: Simple Calculations Using Molar Volume -->\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">4<\/div><h2>Simple Calculations Using the Molar Volume<\/h2><\/div>\n        <p>The molar volume can be used in two directions: to find the <strong>volume<\/strong> from a known mass, or to find the <strong>mass<\/strong> from a known volume. The strategy is always the same; convert to moles first.<\/p>\n\n        <div class=\"ols-worked-example\">\n          <h3>Example A : Volume from mass<\/h3>\n          <p>Calculate the volume of <strong>0.01 g of hydrogen<\/strong> at r.t.p. (H = 1, so 1 mol H<sub>2<\/sub> = 2 g).<\/p>\n          <div class=\"ols-calc-row\">\n            <div class=\"ols-calc-cell\"><span>Step 1: moles of H<sub>2<\/sub><\/span>0.01 \u00f7 2 = <strong>0.005 mol<\/strong><\/div>\n            <div class=\"ols-calc-cell\"><span>Step 2: volume<\/span>0.005 \u00d7 24 = <strong>0.12 dm<sup>3<\/sup><\/strong><\/div>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-worked-example\">\n          <h3>Example B : Mass from volume<\/h3>\n          <p>Calculate the mass of <strong>100 cm<sup>3<\/sup> of CO<sub>2<\/sub><\/strong> at r.t.p. (C = 12, O = 16, so 1 mol CO<sub>2<\/sub> = 44 g).<\/p>\n          <div class=\"ols-calc-row\">\n            <div class=\"ols-calc-cell\"><span>Step 1: moles of CO<sub>2<\/sub><\/span>100 \u00f7 24 000 = <strong>0.00417 mol<\/strong><\/div>\n            <div class=\"ols-calc-cell\"><span>Step 2: mass<\/span>0.00417 \u00d7 44 = <strong>0.183 g<\/strong><\/div>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Exam tip:<\/strong> convert cm<sup>3<\/sup> values into dm<sup>3<\/sup> by dividing by 1000, or use 24 000 cm<sup>3<\/sup> mol<sup>\u22121<\/sup> directly. Mixing units is the most common source of error in molar volume questions.<\/p>\n        <\/div>\n      <\/article>\n\n      <!-- H5P Card ID 315 -->\n      <section class=\"ols-h5p-card\">\n        <h2>Check Your Understanding: Molar Volume Basics<\/h2>\n        <p>Use this activity to practise converting between moles, mass and gas volumes using the molar volume at r.t.p.<\/p>\n        <div class=\"ols-h5p-grid\">\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-315\" class=\"h5p-iframe\" data-content-id=\"315\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Gas Volume and Density Calculations Practice\"><\/iframe><\/div><\/div>\n        <\/div>\n      <\/section>\n\n      <!-- Card 5: Calculations from Equations Involving Gases -->\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">5<\/div><h2>Calculations From Equations Involving Gases<\/h2><\/div>\n        <p>When a balanced equation involves gases, you can use the molar volume together with the stoichiometric ratio to convert between gas volumes and masses, or between volumes of different gases.<\/p>\n        <p>The general strategy has three steps:<\/p>\n        <div class=\"ols-rule-list\">\n          <div class=\"ols-rule-item\">\n            <h3>Step 1 : Convert the given quantity into moles<\/h3>\n            <p>Use mass \u2192 moles (divide by M<sub>r<\/sub>) or volume \u2192 moles (divide by 24 dm<sup>3<\/sup> mol<sup>\u22121<\/sup> at r.t.p.).<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Step 2 : Apply the mole ratio<\/h3>\n            <p>Use the balancing numbers from the balanced equation to convert the moles of the known substance into moles of the substance you need.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Step 3 : Convert moles into the required answer<\/h3>\n            <p>Use moles \u2192 mass (multiply by M<sub>r<\/sub>) or moles \u2192 volume (multiply by 24 dm<sup>3<\/sup> mol<sup>\u22121<\/sup>).<\/p>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-worked-example\">\n          <h3>Example C : Mass of aluminium for a fixed gas volume<\/h3>\n          <p>A student produces hydrogen by reacting aluminium with excess dilute hydrochloric acid. The hydrogen is collected in a 100 cm<sup>3<\/sup> gas syringe at r.t.p. What is the maximum mass of aluminium that can be used without exceeding the syringe capacity? (Al = 27, molar volume = 24 000 cm<sup>3<\/sup> at r.t.p.)<\/p>\n          <p><strong>Balanced equation:<\/strong> 2Al + 6HCl \u2192 2AlCl<sub>3<\/sub> + 3H<sub>2<\/sub><\/p>\n          <div class=\"ols-calc-row\">\n            <div class=\"ols-calc-cell\"><span>Mole ratio<\/span>2 mol Al gives 3 mol H<sub>2<\/sub><\/div>\n            <div class=\"ols-calc-cell\"><span>By mass and volume<\/span>54 g Al gives 72 000 cm<sup>3<\/sup> H<sub>2<\/sub><\/div>\n            <div class=\"ols-calc-cell\"><span>Mass of Al for 100 cm<sup>3<\/sup> H<sub>2<\/sub><\/span>(54 \u00f7 72 000) \u00d7 100 = <strong>0.075 g<\/strong><\/div>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-worked-example\">\n          <h3>Example D : Reacting volumes of gases<\/h3>\n          <p>500 cm<sup>3<\/sup> of methane is burned at 1 atm and 300 K. Calculate the volume of oxygen needed and the volume of CO<sub>2<\/sub> produced under the same conditions.<\/p>\n          <p><strong>Balanced equation:<\/strong> CH<sub>4<\/sub>(g) + 2O<sub>2<\/sub>(g) \u2192 CO<sub>2<\/sub>(g) + 2H<sub>2<\/sub>O(l)<\/p>\n          <p>Because Avogadro&#8217;s law applies, the volume ratio matches the mole ratio for gases at the same conditions. CH<sub>4<\/sub> : O<sub>2<\/sub> : CO<sub>2<\/sub> is 1 : 2 : 1.<\/p>\n          <div class=\"ols-calc-row\">\n            <div class=\"ols-calc-cell\"><span>Volume of O<sub>2<\/sub><\/span>500 \u00d7 2 = <strong>1000 cm<sup>3<\/sup><\/strong><\/div>\n            <div class=\"ols-calc-cell\"><span>Volume of CO<sub>2<\/sub><\/span>500 \u00d7 1 = <strong>500 cm<sup>3<\/sup><\/strong><\/div>\n          <\/div>\n          <p>Water is a liquid under these conditions and so does not contribute to the gas volume.<\/p>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Reacting volumes shortcut:<\/strong> for gas-only reactions, you can skip the conversion to moles entirely and just apply the volume ratio directly, as long as all gases are at the same temperature and pressure.<\/p>\n        <\/div>\n      <\/article>\n\n      <!-- Image 4: Gas volume calculations \/ measuring with syringe -->\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\/Gas-volume-calculations-in-chemistry.webp\" alt=\"Gas volume calculations in chemistry showing the link between balanced equations and reacting gas volumes\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>The stoichiometric numbers in a balanced equation map directly onto gas volumes when every reacting species is in the gas phase.<\/p>\n        <\/div>\n      <\/div>\n\n      <!-- H5P Card ID 316 -->\n      <section class=\"ols-h5p-card\">\n        <h2>Check Your Understanding: Reacting Gas Volumes<\/h2>\n        <p>Practise using balanced equations with the molar volume to find masses and volumes from gas reaction data.<\/p>\n        <div class=\"ols-h5p-grid\">\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-316\" class=\"h5p-iframe\" data-content-id=\"316\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Gas Preparation Calculations Practice\"><\/iframe><\/div><\/div>\n        <\/div>\n      <\/section>\n\n      <!-- Card 6: The Ideal Gas Equation -->\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">6<\/div><h2>The Ideal Gas Equation<\/h2><\/div>\n        <p>The molar volume value of 24 dm<sup>3<\/sup> mol<sup>\u22121<\/sup> only works at room temperature and pressure. For any other temperature or pressure, use the <strong>ideal gas equation<\/strong>:<\/p>\n\n        <div class=\"ols-equation-box\">\n          <strong>pV = nRT<\/strong>\n        <\/div>\n\n        <p>Where the quantities and their SI units are:<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Symbol<\/th>\n                <th>Quantity<\/th>\n                <th>SI unit<\/th>\n                <th>Conversion notes<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Symbol\">p<\/td>\n                <td data-label=\"Quantity\">Pressure<\/td>\n                <td data-label=\"SI unit\">Pa (pascal)<\/td>\n                <td data-label=\"Conversion notes\">1 kPa = 1000 Pa; 1 atm = 101 325 Pa.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Symbol\">V<\/td>\n                <td data-label=\"Quantity\">Volume<\/td>\n                <td data-label=\"SI unit\">m<sup>3<\/sup><\/td>\n                <td data-label=\"Conversion notes\">1 dm<sup>3<\/sup> = 1 \u00d7 10<sup>\u22123<\/sup> m<sup>3<\/sup>; 1 cm<sup>3<\/sup> = 1 \u00d7 10<sup>\u22126<\/sup> m<sup>3<\/sup>.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Symbol\">n<\/td>\n                <td data-label=\"Quantity\">Amount of gas<\/td>\n                <td data-label=\"SI unit\">mol<\/td>\n                <td data-label=\"Conversion notes\">Use mol directly.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Symbol\">R<\/td>\n                <td data-label=\"Quantity\">Gas constant<\/td>\n                <td data-label=\"SI unit\">J K<sup>\u22121<\/sup> mol<sup>\u22121<\/sup><\/td>\n                <td data-label=\"Conversion notes\">R = 8.31 J K<sup>\u22121<\/sup> mol<sup>\u22121<\/sup>.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Symbol\">T<\/td>\n                <td data-label=\"Quantity\">Temperature<\/td>\n                <td data-label=\"SI unit\">K (kelvin)<\/td>\n                <td data-label=\"Conversion notes\">Add 273 to convert \u00b0C to K.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Key idea:<\/strong> the ideal gas equation applies to all gases and to mixtures of gases. For a mixture, n is the total moles of all gases present.<\/p>\n        <\/div>\n        <div class=\"ols-definition-box\">\n          <p><strong>Unit warning:<\/strong> almost every mark lost in ideal gas questions comes from unit conversion errors. Convert pressure to Pa, volume to m<sup>3<\/sup> and temperature to K <em>before<\/em> substituting any numbers.<\/p>\n        <\/div>\n      <\/article>\n\n      <!-- Image 5: Ideal gas equation infographic -->\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\/The-ideal-gas-equation-infographic.webp\" alt=\"The ideal gas equation pV = nRT infographic with units and conversions\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>Memorising the equation is the easy part; converting every quantity into SI units before substituting is what separates a correct answer from a wrong one.<\/p>\n        <\/div>\n      <\/div>\n\n      <!-- Card 7: Ideal Gas Equation Examples -->\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">7<\/div><h2>Ideal Gas Equation Worked Examples<\/h2><\/div>\n\n        <div class=\"ols-worked-example\">\n          <h3>Example E : Finding mass of a gas<\/h3>\n          <p>Calculate the mass of Cl<sub>2<\/sub> gas at a pressure of 100 kPa, temperature 20 \u00b0C and volume 500 cm<sup>3<\/sup>. (Cl = 35.5; R = 8.31)<\/p>\n          <div class=\"ols-calc-row\">\n            <div class=\"ols-calc-cell\"><span>Pressure<\/span>100 kPa = 100 000 Pa<\/div>\n            <div class=\"ols-calc-cell\"><span>Volume<\/span>500 cm<sup>3<\/sup> = 5 \u00d7 10<sup>\u22124<\/sup> m<sup>3<\/sup><\/div>\n            <div class=\"ols-calc-cell\"><span>Temperature<\/span>20 + 273 = 293 K<\/div>\n          <\/div>\n          <p><strong>n = pV \/ RT<\/strong> = (100 000 \u00d7 5 \u00d7 10<sup>\u22124<\/sup>) \/ (8.31 \u00d7 293) = <strong>0.0205 mol<\/strong><\/p>\n          <p><strong>Mass<\/strong> = n \u00d7 M<sub>r<\/sub> = 0.0205 \u00d7 71 = <strong>1.46 g<\/strong><\/p>\n        <\/div>\n\n        <div class=\"ols-worked-example\">\n          <h3>Example F : Finding the relative formula mass of a volatile liquid<\/h3>\n          <p>0.150 g of a volatile liquid was injected into a sealed gas syringe placed in an oven at 70 \u00b0C. The pressure was 100 kPa and the measured gas volume was 80 cm<sup>3<\/sup>. Calculate the M<sub>r<\/sub> of the liquid. (R = 8.31)<\/p>\n          <div class=\"ols-calc-row\">\n            <div class=\"ols-calc-cell\"><span>Pressure<\/span>100 000 Pa<\/div>\n            <div class=\"ols-calc-cell\"><span>Volume<\/span>80 cm<sup>3<\/sup> = 8 \u00d7 10<sup>\u22125<\/sup> m<sup>3<\/sup><\/div>\n            <div class=\"ols-calc-cell\"><span>Temperature<\/span>70 + 273 = 343 K<\/div>\n          <\/div>\n          <p><strong>n = pV \/ RT<\/strong> = (100 000 \u00d7 8 \u00d7 10<sup>\u22125<\/sup>) \/ (8.31 \u00d7 343) = <strong>0.00281 mol<\/strong><\/p>\n          <p><strong>M<sub>r<\/sub><\/strong> = mass \/ amount = 0.150 \/ 0.00281 = <strong>53.4 g mol<sup>\u22121<\/sup><\/strong><\/p>\n        <\/div>\n\n        <div class=\"ols-worked-example\">\n          <h3>Example G : Changing the conditions of a gas<\/h3>\n          <p>40 cm<sup>3<\/sup> of oxygen and 60 cm<sup>3<\/sup> of carbon dioxide, each at 298 K and 100 kPa, were placed into an evacuated flask of volume 0.50 dm<sup>3<\/sup>. Calculate the pressure of the gas mixture in the flask at 298 K.<\/p>\n          <p>Because temperature is constant, the combined gas law simplifies to <strong>p<sub>1<\/sub>V<sub>1<\/sub> = p<sub>2<\/sub>V<sub>2<\/sub><\/strong>.<\/p>\n          <p>Total starting volume of gas at 100 kPa = 40 + 60 = <strong>100 cm<sup>3<\/sup><\/strong>; new volume = 0.50 dm<sup>3<\/sup> = 500 cm<sup>3<\/sup>.<\/p>\n          <p><strong>p<sub>2<\/sub><\/strong> = (p<sub>1<\/sub>V<sub>1<\/sub>) \/ V<sub>2<\/sub> = (100 000 \u00d7 100) \/ 500 = <strong>20 000 Pa<\/strong><\/p>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Approach for changing-conditions questions:<\/strong> either work out the amount in moles using pV = nRT and then put it back into the equation with the new conditions, or use the combined form p<sub>1<\/sub>V<sub>1<\/sub>\/T<sub>1<\/sub> = p<sub>2<\/sub>V<sub>2<\/sub>\/T<sub>2<\/sub>. The combined form is faster when the amount of gas is unchanged.<\/p>\n        <\/div>\n      <\/article>\n\n      <!-- Image 6: Measuring gases with a gas syringe -->\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\/Measuring-gases-with-a-gas-syringe.webp\" alt=\"Measuring gases with a gas syringe in a chemistry experiment\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>Gas syringes are a common apparatus for collecting and measuring gas volumes at known temperature and pressure, which links practical work directly to molar volume and ideal gas calculations.<\/p>\n        <\/div>\n      <\/div>\n\n      <!-- H5P Card ID 317 -->\n      <section class=\"ols-h5p-card\">\n        <h2>Check Your Understanding: The Ideal Gas Equation<\/h2>\n        <p>Apply pV = nRT to find moles, masses, volumes and relative formula masses of gases under any set of conditions.<\/p>\n        <div class=\"ols-h5p-grid\">\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-317\" class=\"h5p-iframe\" data-content-id=\"317\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Ideal Gas Equation Practice\"><\/iframe><\/div><\/div>\n        <\/div>\n      <\/section>\n\n      <!-- Card 8: Common Exam Points -->\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>Avogadro&#8217;s law lets you treat <strong>gas volume ratios as mole ratios<\/strong>, provided every gas is measured at the same temperature and pressure.<\/li>\n          <li>The molar volume at r.t.p. is <strong>24 dm<sup>3<\/sup> mol<sup>\u22121<\/sup><\/strong>, which equals 24 000 cm<sup>3<\/sup> mol<sup>\u22121<\/sup>.<\/li>\n          <li>The molar volume at s.t.p. is <strong>22.4 dm<sup>3<\/sup> mol<sup>\u22121<\/sup><\/strong>. Use whichever value the question specifies.<\/li>\n          <li>Always convert temperature to <strong>kelvin<\/strong> by adding 273 before using pV = nRT.<\/li>\n          <li>Convert pressure to <strong>pascals<\/strong>: 1 kPa = 1000 Pa.<\/li>\n          <li>Convert volume to <strong>m<sup>3<\/sup><\/strong>: divide cm<sup>3<\/sup> by 1 \u00d7 10<sup>6<\/sup>, or dm<sup>3<\/sup> by 1000.<\/li>\n          <li>R = 8.31 J K<sup>\u22121<\/sup> mol<sup>\u22121<\/sup> in SI units. This value only works with Pa, m<sup>3<\/sup> and K.<\/li>\n          <li>For mixtures, n in pV = nRT is the <strong>total<\/strong> moles of every gas in the mixture.<\/li>\n          <li>When conditions change but the moles of gas are constant, use <strong>p<sub>1<\/sub>V<sub>1<\/sub>\/T<sub>1<\/sub> = p<sub>2<\/sub>V<sub>2<\/sub>\/T<sub>2<\/sub><\/strong> directly.<\/li>\n          <li>Show every unit conversion clearly on your script; markers award method marks even if the final number is wrong.<\/li>\n        <\/ul>\n      <\/article>\n\n      <!-- Extension H5P 318 -->\n      <section class=\"ols-h5p-card\">\n        <h2>Extension Questions<\/h2>\n        <p>These extension questions go beyond the standard examples and stretch your application of molar volume and the ideal gas equation in more demanding contexts.<\/p>\n        <div class=\"ols-h5p-grid\">\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-318\" class=\"h5p-iframe\" data-content-id=\"318\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Ideal Gas Laboratory Calculations Practice\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-332\" class=\"h5p-iframe\" data-content-id=\"332\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Total volume of gas after complete combustion of methane with excess oxygen\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-333\" class=\"h5p-iframe\" data-content-id=\"333\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Volume of oxygen using the ideal gas law\"><\/iframe><\/div><\/div>\n        <\/div>\n      <\/section>\n\n      <!-- QuickSnap Summary -->\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>Avogadro&#8217;s law:<\/strong> equal volumes of gases at the same temperature and pressure contain equal numbers of particles.<\/li>\n          <li><strong>Molar volume at r.t.p.:<\/strong> 24 dm<sup>3<\/sup> mol<sup>\u22121<\/sup> = 24 000 cm<sup>3<\/sup> mol<sup>\u22121<\/sup>.<\/li>\n          <li><strong>Moles of gas at r.t.p.:<\/strong> volume in dm<sup>3<\/sup> \u00f7 24, or volume in cm<sup>3<\/sup> \u00f7 24 000.<\/li>\n          <li><strong>Reacting volumes:<\/strong> for gas-only reactions, volume ratio = mole ratio from the balanced equation.<\/li>\n          <li><strong>Ideal gas equation:<\/strong> pV = nRT, using Pa, m<sup>3<\/sup>, mol, J K<sup>\u22121<\/sup> mol<sup>\u22121<\/sup> and K.<\/li>\n          <li><strong>R = 8.31<\/strong> J K<sup>\u22121<\/sup> mol<sup>\u22121<\/sup>.<\/li>\n          <li><strong>Temperature:<\/strong> always convert \u00b0C to K by adding 273.<\/li>\n          <li><strong>Changing conditions:<\/strong> p<sub>1<\/sub>V<sub>1<\/sub>\/T<sub>1<\/sub> = p<sub>2<\/sub>V<sub>2<\/sub>\/T<sub>2<\/sub> when the amount of gas is unchanged.<\/li>\n          <li><strong>Finding M<sub>r<\/sub> of a gas:<\/strong> use pV = nRT to find moles, then M<sub>r<\/sub> = mass \/ moles.<\/li>\n        <\/ul>\n      <\/section>\n\n      <!-- Lightbox element -->\n      <div class=\"ols-image-lightbox\" id=\"olsImageLightboxMolarVolume001\" 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 = 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border-bottom-width: 14px;\r\n        border-left-width: 22px;\r\n      }\r\n\r\n      .ols-course-cta-formulae-amounts .ols-animation-pause-button {\r\n        left: 12px;\r\n        bottom: 12px;\r\n        min-width: 84px;\r\n        padding: 9px 14px;\r\n        font-size: 13px;\r\n      }\r\n\r\n      .ols-course-cta-formulae-amounts .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  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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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This value applies to every gas because of Avogadro&#8217;s law.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Why do all gases have the same molar volume?<\/h3>\n            <p>Avogadro&#8217;s law states that equal volumes of gases at the same temperature and pressure contain equal numbers of particles. The size of the particles makes almost no difference compared with the space between them, so all gases occupy the same volume per mole under the same conditions.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>When do I use pV = nRT instead of the molar volume value?<\/h3>\n            <p>Use the molar volume value (24 dm<sup>3<\/sup> mol<sup>\u22121<\/sup>) only at r.t.p. For any other temperature or pressure, use the ideal gas equation pV = nRT with consistent SI units of Pa, m<sup>3<\/sup>, mol and K.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>What units must I use in the ideal gas equation?<\/h3>\n            <p>Pressure in pascals (Pa), volume in cubic metres (m<sup>3<\/sup>), amount in moles (mol), R in J K<sup>\u22121<\/sup> mol<sup>\u22121<\/sup> (8.31), and temperature in kelvin (K). Convert \u00b0C to K by adding 273, kPa to Pa by multiplying by 1000, and cm<sup>3<\/sup> to m<sup>3<\/sup> by multiplying by 1 \u00d7 10<sup>\u22126<\/sup>.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>How do I handle a mixture of gases in pV = nRT?<\/h3>\n            <p>In a mixture, n is the total number of moles of all gases combined. The equation applies to the mixture as a whole, provided the gases do not react with each other.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>How do I find the relative formula mass of a volatile liquid?<\/h3>\n            <p>Vaporise a known mass of the liquid into a sealed gas syringe at a known temperature and pressure. Use pV = nRT to find the moles of vapour produced, then calculate M<sub>r<\/sub> using M<sub>r<\/sub> = mass \/ moles.<\/p>\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <!-- Related Topics -->\n      <section class=\"ols-related-card\">\n        <h2>Related Topics<\/h2>\n        <p>Build the surrounding skills needed to work confidently with gas calculations and the mole concept.<\/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\/mole-calculations\/calculations-involving-moles\/\">Calculations Involving Moles<\/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\/calculations-with-solutions-and-gases\/\">Calculations with Solutions<\/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\/empirical-and-molecular-formulae\/empirical-formulae\/\">Empirical Formula<\/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\/empirical-and-molecular-formulae\/molecular-formulae\/\">Molecular Formula<\/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\/calculations-using-reacting-masses\/\">Calculations Using Reacting Masses<\/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\/\">Topic 5 Overview<\/a>\n        <\/div>\n      <\/section>\n\n      <!-- Copyright attribution -->\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      <!-- JSON-LD Schema -->\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\/calculations-with-solutions-and-gases\/molar-volume-calculations\/#webpage\",\n            \"url\": \"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\/\",\n            \"name\": \"Molar Volume Calculations - Edexcel A Level Chemistry Revision Notes\",\n            \"description\": \"Learn molar volume calculations, Avogadro's law and the ideal gas equation pV = nRT for Edexcel A Level Chemistry Topic 5. 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Convert degrees Celsius to K by adding 273, kPa to Pa by multiplying by 1000, and cm3 to m3 by multiplying by 1 times 10 to the power minus 6.\"\n                }\n              },\n              {\n                \"@type\": \"Question\",\n                \"name\": \"How do I handle a mixture of gases in pV = nRT?\",\n                \"acceptedAnswer\": {\n                  \"@type\": \"Answer\",\n                  \"text\": \"In a mixture, n is the total number of moles of all gases combined. 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Use pV = nRT to find the moles of vapour produced, then calculate Mr using Mr = mass divided by moles.\"\n                }\n              }\n            ]\n          },\n          {\n            \"@type\": \"ImageObject\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Avogadros-law-explained-visually.webp#image\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Avogadros-law-explained-visually.webp\",\n            \"name\": \"Avogadro's law explained visually\",\n            \"description\": \"A visual explanation of Avogadro's law showing equal volumes of different gases at the same temperature and pressure containing equal numbers of particles.\"\n          },\n          {\n            \"@type\": \"ImageObject\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Understanding-molar-volume-of-a-gas.webp#image\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Understanding-molar-volume-of-a-gas.webp\",\n            \"name\": \"Understanding the molar volume of a gas\",\n            \"description\": \"A visual representation of the molar volume concept and how it relates to one mole of any gas at fixed conditions.\"\n          },\n          {\n            \"@type\": \"ImageObject\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Calculating-molar-volume-of-oxygen.webp#image\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Calculating-molar-volume-of-oxygen.webp\",\n            \"name\": \"Calculating the molar volume of oxygen\",\n            \"description\": \"A worked illustration showing how the molar volume applies to oxygen gas at room temperature and pressure.\"\n          },\n          {\n            \"@type\": \"ImageObject\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Gas-volume-calculations-in-chemistry.webp#image\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Gas-volume-calculations-in-chemistry.webp\",\n            \"name\": \"Gas volume calculations in chemistry\",\n            \"description\": \"A diagram showing how balanced equations are used to calculate reacting volumes of gases under the same conditions.\"\n          },\n          {\n            \"@type\": \"ImageObject\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/The-ideal-gas-equation-infographic.webp#image\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/The-ideal-gas-equation-infographic.webp\",\n            \"name\": \"The ideal gas equation infographic\",\n            \"description\": \"An infographic summarising the ideal gas equation pV = nRT, its variables and their required SI units.\"\n          },\n          {\n            \"@type\": \"ImageObject\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Measuring-gases-with-a-gas-syringe.webp#image\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Measuring-gases-with-a-gas-syringe.webp\",\n            \"name\": \"Measuring gases with a gas syringe\",\n            \"description\": \"A photograph or illustration of a chemistry experiment using a gas syringe to measure the volume of a gas at known conditions.\"\n          }\n        ]\n      }\n      <\/script>\n    <\/main>\n  <\/div>\n<\/section>\n","protected":false},"excerpt":{"rendered":"<p>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 focused revision guide to molar volume calculations for Edexcel A Level Chemistry. 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