{"id":8081,"date":"2026-09-15T08:24:28","date_gmt":"2026-09-15T07:24:28","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/the-yield-of-a-reaction\/"},"modified":"2026-09-24T11:05:44","modified_gmt":"2026-09-24T10:05:44","slug":"the-yield-of-a-reaction","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/the-yield-of-a-reaction\/","title":{"rendered":"The Yield of a Reaction"},"content":{"rendered":"\n<!--\n===============================================================================\nONLINE LEARNING SYSTEM COPYRIGHT NOTICE\n\u00a9 Online Learning System. 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class=\"ols-topic-group\">\n    <h4>Topic 2 Atoms, Molecules and Stoichiometry<\/h4>\n    <ul class=\"ols-topic-list\">\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/\">Topic overview<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/atoms-elements-and-molecules\/\">2.1 \/ 2.2 Atoms, Elements and Molecules<\/a><\/li>\n<li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/ions-and-ionic-formulae\/\">2.3 Ions and Ionic Formulae<\/a><\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/equations-and-reaction-types\/\">2.3 Equations and Reaction Types<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/equations-and-reaction-types\/writing-chemical-equations\/\">Writing Chemical Equations<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/equations-and-reaction-types\/typical-reactions-of-acids\/\">Typical Reactions of Acids<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/equations-and-reaction-types\/ionic-and-full-equations\/\">Ionic and Full Equations<\/a><\/li>\n        <\/ul>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/empirical-and-molecular-formulae\/\">2.3 Empirical and Molecular Formulae<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/empirical-and-molecular-formulae\/empirical-formulae\/\">Empirical Formulae<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/empirical-and-molecular-formulae\/molecular-formulae\/\">Molecular Formulae<\/a><\/li>\n<li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/hydrated-salts-and-water-of-crystallisation\/\">2.3 Hydrated Salts and Water of Crystallisation<\/a><\/li>\n        <\/ul>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/\">2.4 Mole Calculations<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/comparing-masses-of-substances\/\">Comparing Masses of Substances<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/calculations-involving-moles\/\">Calculations involving Moles<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/calculations-using-reacting-masses\/\">Calculations using Reacting Masses<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/the-yield-of-a-reaction\/\">The Yield of a Reaction<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/atom-economy\/\">Atom Economy<\/a><\/li>\n        <\/ul>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/calculations-with-solutions-and-gases\/\">2.4 Solutions and Gases<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/calculations-with-solutions-and-gases\/molar-volume-calculations\/\">Molar Volume Calculations<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/calculations-with-solutions-and-gases\/concentrations-of-solutions\/\">Concentrations of Solutions<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/calculations-with-solutions-and-gases\/titration-calculations\/\">Titration Calculations<\/a><\/li>\n        <\/ul>\n      <\/li>\n    <\/ul>\n  <\/div>\n  <div class=\"ols-topic-group\">\n    <h4>Other Topics<\/h4>\n    <ul class=\"ols-topic-list\">\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-1-atomic-structure\/\">Topic 1 Atomic Structure<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-3-chemical-bonding\/\">Topic 3 Chemical Bonding<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-4-states-of-matter\/\">Topic 4 States of Matter<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-9-the-periodic-table-chemical-periodicity\/\">Topic 9 Chemical Periodicity<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/\">Topic 13 Introduction to Organic Chemistry<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-14-hydrocarbons\/\">Topic 14 Hydrocarbons<\/a><\/li>\n    <\/ul>\n  <\/div>\n<\/aside>\n<script>\r\n(function() {\r\n  function normalisePath(path) {\r\n    return String(path || '')\r\n      .split('?')[0]\r\n      .split('#')[0]\r\n      .replace(\/\\\/+$\/, '')\r\n      .toLowerCase();\r\n  }\r\n\r\n  function highlightActive() {\r\n    var sidebar = document.querySelector('.ols-sidebar');\r\n    if (!sidebar) return false;\r\n\r\n    var currentPath = normalisePath(window.location.pathname);\r\n    var links = sidebar.querySelectorAll('a[href]');\r\n    var matched = null;\r\n    var matchedLength = 0;\r\n\r\n    sidebar.querySelectorAll('.active, .active-main, .parent-active').forEach(function(item) {\r\n      item.classList.remove('active', 'active-main', 'parent-active');\r\n    });\r\n\r\n    sidebar.querySelectorAll('a[data-ols-disabled-parent=\"1\"], 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href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/\">Mole Calculations<\/a> \/\n<span>The Yield of a Reaction<\/span>\n<\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>The Yield of a Reaction<\/h1>\n        <p class=\"ols-page-intro\">A focused revision guide to percentage yield, actual yield and theoretical yield. This page links mole calculations to practical chemistry, where reactions rarely give the maximum possible amount of product.<\/p>\n\n        <div class=\"ols-badges\">\n<div class=\"ols-badge\">AS Level<\/div>\n<div class=\"ols-badge\">Topic 2: Atoms, Molecules and Stoichiometry<\/div>\n<div class=\"ols-badge\">9701 Papers 1 and 2<\/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>Why Yield Matters<\/h2><\/div>\n        <p>In ideal mole calculations, the balanced equation predicts the maximum mass of product that could be formed. In real practical chemistry, the amount collected is often lower than this maximum.<\/p>\n        <p>This is especially common in organic chemistry, where <strong>side reactions<\/strong>, transfers between containers, purification steps and incomplete reactions can reduce the final mass of pure product.<\/p>\n        <div class=\"ols-key-box\"><p><strong>Key idea:<\/strong> yield calculations connect theoretical chemistry to the practical reality of making and isolating a product.<\/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>Actual Yield and Theoretical Yield<\/h2><\/div>\n        <p>To calculate percentage yield, you need to compare two quantities: the mass of product that was actually obtained and the maximum mass that could have been obtained from the reactants.<\/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>How it is found<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Term\">Actual yield<\/td>\n                <td data-label=\"Meaning\">The amount of product collected in the experiment.<\/td>\n                <td data-label=\"How it is found\">Measured directly in the practical or stated in the question.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Term\">Theoretical yield<\/td>\n                <td data-label=\"Meaning\">The maximum amount of product that could be made if the reaction went perfectly.<\/td>\n                <td data-label=\"How it is found\">Calculated from the balanced equation using mole ratios.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Term\">Percentage yield<\/td>\n                <td data-label=\"Meaning\">The actual yield expressed as a percentage of the theoretical yield.<\/td>\n                <td data-label=\"How it is found\">Use actual yield \u00f7 theoretical yield \u00d7 100.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Actual or Theoretical?<\/h2>\n<p>Decide quickly which yield each situation describes or changes.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-626\" class=\"h5p-iframe\" data-content-id=\"626\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Percentage Yield Quick-Fire: Actual or Theoretical?\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card purple ols-zoom-section\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">3<\/div><h2>The Percentage Yield Formula<\/h2><\/div>\n        <p>The percentage yield formula compares what you obtained with what you could theoretically have obtained.<\/p>\n        <div class=\"ols-definition-box\"><p><strong>Percentage yield = actual yield \u00f7 theoretical yield \u00d7 100<\/strong><\/p><\/div>\n        <p>Both yields must use the <strong>same unit<\/strong>. If the actual yield is in grams, the theoretical yield must also be in grams. If the actual yield is in moles, the theoretical yield must also be in moles.<\/p>\n        <div class=\"ols-key-box\"><p><strong>Exam focus:<\/strong> the theoretical yield is not measured in the lab. It is calculated from the balanced equation.<\/p><\/div>\n\n        <figure class=\"ols-zoom-card\">\n          <div class=\"ols-zoom-card-image\">\n            <img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/wave-33.jpg\" alt=\"Worked percentage yield for hex-1-ene, with the stray bracket removed from the Stage 2 heading.\">\n          <\/div>\n          <figcaption class=\"ols-zoom-card-caption\"><p>Use the formula only after the theoretical yield has been calculated from the balanced equation.<\/p><\/figcaption>\n        <\/figure>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Use the Formula Three Ways<\/h2>\n<p>Type each answer to 3 significant figures, checking the units first.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-627\" class=\"h5p-iframe\" data-content-id=\"627\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Percentage Yield Fill in the Blanks: Using and Rearranging the Formula\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">4<\/div><h2>Calculating Theoretical Yield First<\/h2><\/div>\n        <p>Most exam questions do not give the theoretical yield directly. You usually calculate it first using moles, the balanced equation and relative formula mass.<\/p>\n        <div class=\"ols-rule-list\">\n          <div class=\"ols-rule-item\">\n            <h3>Step 1: calculate the amount of reactant<\/h3>\n            <p>Use <strong>amount = mass \u00f7 molar mass<\/strong>.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Step 2: use the mole ratio<\/h3>\n            <p>Use the coefficients in the balanced equation to convert from reactant moles to product moles.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Step 3: calculate the theoretical mass<\/h3>\n            <p>Use <strong>mass = amount \u00d7 molar mass<\/strong>.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Step 4: calculate percentage yield<\/h3>\n            <p>Compare the actual yield with the theoretical yield, then multiply by 100.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Order the Yield Calculation<\/h2>\n<p>Drag the steps of this percentage yield calculation into the right order.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-628\" class=\"h5p-iframe\" data-content-id=\"628\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Percentage Yield Put in Order: Magnesium Oxide Route\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">5<\/div><h2>Worked Example: Iron from Iron(III) Oxide<\/h2><\/div>\n        <p><strong>Question:<\/strong> 25.0 g of Fe<sub>2<\/sub>O<sub>3<\/sub> reacts with carbon monoxide and 10.0 g of Fe is produced. Calculate the percentage yield.<\/p>\n        <p><strong>Balanced equation:<\/strong> Fe<sub>2<\/sub>O<sub>3<\/sub> + 3CO \u2192 2Fe + 3CO<sub>2<\/sub><\/p>\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Stage<\/th>\n                <th>Working<\/th>\n                <th>Result<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Stage\">Amount of Fe<sub>2<\/sub>O<sub>3<\/sub><\/td>\n                <td data-label=\"Working\">M<sub>r<\/sub> of Fe<sub>2<\/sub>O<sub>3<\/sub> = 159.6<br>amount = 25.0 \u00f7 159.6<\/td>\n                <td data-label=\"Result\">0.1566 mol<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Stage\">Mole ratio<\/td>\n                <td data-label=\"Working\">1 mol Fe<sub>2<\/sub>O<sub>3<\/sub> produces 2 mol Fe<\/td>\n                <td data-label=\"Result\">0.3132 mol Fe<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Stage\">Theoretical mass of Fe<\/td>\n                <td data-label=\"Working\">mass = amount \u00d7 M<sub>r<\/sub><br>mass = 0.3132 \u00d7 55.8<\/td>\n                <td data-label=\"Result\">17.5 g Fe<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Stage\">Percentage yield<\/td>\n                <td data-label=\"Working\">percentage yield = 10.0 \u00f7 17.5 \u00d7 100<\/td>\n                <td data-label=\"Result\">57.1%<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n        <div class=\"ols-key-box\"><p><strong>Answer:<\/strong> the percentage yield is <strong>57.1%<\/strong>, because only 10.0 g of iron was obtained from a possible 17.5 g.<\/p><\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Percentage Yield from Masses<\/h2>\n<p>Work each calculation out on paper before you turn the card.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-310\" class=\"h5p-iframe\" data-content-id=\"310\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Percentage Yield Flip Cards: Theoretical Yield First\"><\/iframe><\/div><\/div>\n<\/section>\n\n      \n\n      <article class=\"ols-note-card ols-zoom-section\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">6<\/div><h2>Using Density in Yield Calculations<\/h2><\/div>\n        <p>Sometimes a practical gives a product volume rather than a product mass. If the product is a liquid and its density is given, calculate the mass before calculating the yield.<\/p>\n        <div class=\"ols-definition-box\"><p><strong>mass = density \u00d7 volume<\/strong><\/p><\/div>\n        <p>Check the units carefully. If density is given in g cm<sup>-3<\/sup>, volume should be in cm<sup>3<\/sup>, giving mass in grams.<\/p>\n\n        <figure class=\"ols-zoom-card\">\n          <div class=\"ols-zoom-card-image\">\n            <img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/wave-34.jpg\" alt=\"Density-to-yield worked example, with molar masses labelled M in g mol\u207b\u00b9 and sulfuric acid spelled with an f.\">\n          <\/div>\n          <figcaption class=\"ols-zoom-card-caption\"><p>When a liquid product is measured by volume, density converts the volume into the mass needed for the percentage yield calculation.<\/p><\/figcaption>\n        <\/figure>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: A Liquid Product<\/h2>\n<p>Convert the volume of product into a mass before you calculate the yield.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-311\" class=\"h5p-iframe\" data-content-id=\"311\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Percentage Yield MCQ: Liquid Product Measured by Volume\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">7<\/div><h2>Why Yield Is Less Than 100%<\/h2><\/div>\n        <p>A reaction often has a percentage yield below 100% because the theoretical yield assumes perfect conditions. Practical chemistry involves losses and limitations.<\/p>\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Reason<\/th>\n                <th>How it lowers yield<\/th>\n                <th>Example wording<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Reason\">Incomplete reaction<\/td>\n                <td data-label=\"How it lowers yield\">Not all reactant particles are converted into product.<\/td>\n                <td data-label=\"Example wording\">The reaction may not go to completion.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Reason\">Side reactions<\/td>\n                <td data-label=\"How it lowers yield\">Some reactant forms unwanted products instead of the desired product.<\/td>\n                <td data-label=\"Example wording\">A competing reaction uses some starting material.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Reason\">Transfer losses<\/td>\n                <td data-label=\"How it lowers yield\">Product may be left on glassware, filter paper or inside apparatus.<\/td>\n                <td data-label=\"Example wording\">Some product is lost during transfer.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Reason\">Purification losses<\/td>\n                <td data-label=\"How it lowers yield\">Recrystallisation, filtration, washing or drying may remove some product.<\/td>\n                <td data-label=\"Example wording\">Some product is lost during purification.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Explain a Low Yield<\/h2>\n<p>Write a short explanation, then compare it with the mark points and the model answer.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-629\" class=\"h5p-iframe\" data-content-id=\"629\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Percentage Yield Explain: Where the Ester Went\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <section class=\"ols-infographic-full\" aria-label=\"Percentage yield study guide visual summary\">\n        <h2 class=\"ols-infographic-title\">Percentage Yield Study Guide<\/h2>\n        <figure class=\"ols-zoom-card\">\n          <div class=\"ols-zoom-card-image\">\n            <img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Chemistry-percentage-yield-study-guide.webp\" alt=\"Chemistry percentage yield study guide infographic showing actual yield, theoretical yield and reasons for low yield.\">\n          <\/div>\n          <figcaption class=\"ols-zoom-card-caption\"><p>A compact visual summary linking actual yield, theoretical yield and the practical reasons why yields are often below 100%.<\/p><\/figcaption>\n        <\/figure>\n      <\/section>\n\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">8<\/div><h2>Common Exam Points<\/h2><\/div>\n        <ul>\n          <li><strong>Actual yield<\/strong> is the mass of product obtained in the experiment.<\/li>\n          <li><strong>Theoretical yield<\/strong> is the maximum mass predicted by the balanced equation.<\/li>\n          <li><strong>Percentage yield<\/strong> is calculated using actual yield \u00f7 theoretical yield \u00d7 100.<\/li>\n          <li>Use the balanced equation to work out the theoretical yield before using the percentage yield formula.<\/li>\n          <li>The actual yield and theoretical yield must be in the same units.<\/li>\n          <li>Percentage yield below 100% can be caused by incomplete reactions, side reactions and product loss.<\/li>\n          <li>A result above 100% usually indicates impurity, wet product or experimental error.<\/li>\n        <\/ul>\n      <\/article>\n\n      \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>Actual yield:<\/strong> the amount of product collected in the experiment.<\/li>\n          <li><strong>Theoretical yield:<\/strong> the maximum amount predicted by the balanced equation.<\/li>\n          <li><strong>Percentage yield:<\/strong> actual yield \u00f7 theoretical yield \u00d7 100.<\/li>\n          <li><strong>Main method:<\/strong> calculate theoretical yield first, then compare it with the actual yield.<\/li>\n          <li><strong>Low yield:<\/strong> usually caused by incomplete reaction, side reaction, transfer loss or purification loss.<\/li>\n          <li><strong>Exam warning:<\/strong> a yield greater than 100% suggests a problem such as wet or impure product.<\/li>\n        <\/ul>\n      <\/section>\n\n      <div class=\"ols-image-lightbox\" id=\"olsImageLightboxYieldOfReaction001\" aria-hidden=\"true\" role=\"dialog\" aria-label=\"Expanded revision image\">\n        <div class=\"ols-image-lightbox-inner\">\n          <img decoding=\"async\" class=\"ols-image-lightbox-img\" src=\"\" alt=\"\">\n          <button class=\"ols-image-lightbox-close\" type=\"button\" aria-label=\"Close expanded image\">\u00d7<\/button>\n        <\/div>\n      <\/div>\n\n      <script>\n        (function(){\n          var page = document.querySelector(\".ols-yield-of-reaction-page\");\n          if (!page) {\n            return;\n          }\n\n          var lightbox = page.querySelector(\"#olsImageLightboxYieldOfReaction001\");\n          if (!lightbox) {\n            return;\n          }\n\n          var 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         }\n          });\n        })();\n      <\/script>\n\n      <section class=\"ols-faq-card\">\n        <h2>FAQs<\/h2>\n        <p>These questions address common misconceptions students have when learning percentage yield calculations.<\/p>\n        <div class=\"ols-faq-list\">\n          <div class=\"ols-faq-item\">\n            <h3>What is percentage yield?<\/h3>\n            <p>Percentage yield compares the actual amount of product obtained with the theoretical maximum amount predicted by the balanced equation. It is calculated using actual yield \u00f7 theoretical yield \u00d7 100.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>What is the difference between actual yield and theoretical yield?<\/h3>\n            <p>Actual yield is the amount collected in the experiment. Theoretical yield is the maximum possible amount calculated from the balanced equation, assuming no losses and complete reaction.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Why is percentage yield often less than 100%?<\/h3>\n            <p>Yield is often less than 100% because reactions may be incomplete, side reactions may occur, and product may be lost during transfer, filtration, washing, drying or purification.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Can percentage yield be more than 100%?<\/h3>\n            <p>A value above 100% usually indicates an experimental or calculation problem. Common causes include wet product, impurities, weighing errors or using the wrong theoretical yield.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Why do I need the balanced equation for yield calculations?<\/h3>\n            <p>The balanced equation gives the mole ratio between the reactant and product. This ratio is needed to calculate the theoretical yield before the percentage yield can be found.<\/p>\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-related-card\">\n        <h2>Related Topics<\/h2>\n        <p>Build the surrounding calculation skills needed for 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\/cie\/topic-2-atoms-molecules-and-stoichiometry\/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\/cie\/topic-2-atoms-molecules-and-stoichiometry\/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\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/the-yield-of-a-reaction\/\">Percentage Purity<\/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\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/the-yield-of-a-reaction\/#webpage\",\n      \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-2-atoms-molecules-and-stoichiometry\/mole-calculations\/the-yield-of-a-reaction\/\",\n      \"name\": \"The Yield of a Reaction - Cambridge International AS &amp; A Level Chemistry\",\n      \"description\": \"Revise percentage yield, theoretical yield, actual yield and reasons for low yield for Cambridge International AS &amp; A Level Chemistry Topic 2.\",\n      \"inLanguage\": \"en-GB\",\n      \"isPartOf\": {\n        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