{"id":8098,"date":"2026-09-15T08:35:05","date_gmt":"2026-09-15T07:35:05","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-4-acids\/standard-solutions-and-titration-technique\/"},"modified":"2026-09-24T11:05:04","modified_gmt":"2026-09-24T10:05:04","slug":"standard-solutions-and-titration-technique","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-4-acids\/standard-solutions-and-titration-technique\/","title":{"rendered":"Standard Solutions and Titration Technique"},"content":{"rendered":"\n<!--\n===============================================================================\nONLINE LEARNING SYSTEM COPYRIGHT NOTICE\n\u00a9 Online Learning System. 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<p>OCR A Level Chemistry A<\/p>\n  <\/div>\n  <div class=\"ols-topic-group\">\n    <h4>2.1.4 Acids<\/h4>\n    <ul class=\"ols-topic-list\">\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-4-acids\/\">Section overview<\/a><\/li>\n<li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-4-acids\/acids-and-alkalis\/\">Acids and Alkalis<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-4-acids\/typical-reactions-of-acids\/\">Typical Reactions of Acids<\/a><\/li>\n<li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-4-acids\/standard-solutions-and-titration-technique\/\">Standard Solutions and Titration Technique<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-4-acids\/titration-calculations\/\">Titration Calculations<\/a><\/li>\n    <\/ul>\n  <\/div>\n  <div class=\"ols-topic-group\">\n    <h4>Other OCR Sections<\/h4>\n    <ul class=\"ols-topic-list\">\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-1-atomic-structure-and-isotopes\/\">2.1.1 Atomic Structure and Isotopes<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-2-compounds-formulae-and-equations\/\">2.1.2 Compounds, Formulae and Equations<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-3-amount-of-substance\/\">2.1.3 Amount of Substance<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-2-1-electron-structure\/\">2.2.1 Electron Structure<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-2-2-bonding-and-structure\/\">2.2.2 Bonding and Structure<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/3-1-1-periodicity\/\">3.1.1 Periodicity<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-1-1-basic-concepts-of-organic-chemistry\/\">4.1.1 Basic Concepts of Organic Chemistry<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-1-2-alkanes\/\">4.1.2 Alkanes<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-1-3-alkenes\/\">4.1.3 Alkenes<\/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\"], a[aria-current]').forEach(function(a) {\r\n      a.removeAttribute('aria-current');\r\n      a.removeAttribute('tabindex');\r\n      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{\r\n    document.addEventListener('DOMContentLoaded', highlightActive);\r\n  }\r\n})();\r\n<\/script>\n\n  <main class=\"ols-main\">\n      <nav class=\"ols-breadcrumbs\" aria-label=\"Breadcrumb\">\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\">Revision Notes<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\">A Level Chemistry<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/\">OCR A<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-4-acids\/\">2.1.4 Acids<\/a> \/\n<span>Standard Solutions and Titration Technique<\/span>\n<\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Standard Solutions and Titration Technique<\/h1>\n        <p class=\"ols-page-intro\">A concise OCR A Level Chemistry A revision guide to preparing a standard solution of known concentration in a volumetric flask and carrying out an acid-base titration accurately: rinsing, pipetting, indicator choice, rough and accurate titres and concordant results (2.1.4(d)).<\/p>\n\n        <div class=\"ols-badges\">\n<div class=\"ols-badge\">Paper 1 and 2<\/div>\n<div class=\"ols-badge\">2.1.4 Acids<\/div>\n<div class=\"ols-badge\">H432\/01 and H432\/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      <section class=\"ols-h5p-card ols-h5p-inline ols-h5p-recap\">\n<span class=\"ols-h5p-kicker\">Before you start<\/span>\n<h2>GCSE Recap: Concentration, Neutralisation and Dilution<\/h2>\n<p>Before you start, check three ideas from GCSE that this page measures accurately.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"764\"><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">1<\/div>\n<h2>What a Standard Solution Is<\/h2>\n<\/div>\n<p>A <strong>standard solution<\/strong> has an accurately known concentration. It is made by dissolving an accurately weighed mass of a pure solid in water and making the solution up to an exact volume in a <strong>volumetric flask<\/strong>. Its concentration is then c = n \/ V, with n from the mass and V from the flask.<\/p>\n<p>The solid must be a <strong>primary standard<\/strong>: pure, stable in air, not hydrated in a variable way, and of high relative formula mass so that weighing errors are small. Anhydrous sodium carbonate is the classic example; sodium hydroxide is not suitable because it absorbs water and carbon dioxide from the air.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Key idea:<\/strong> A standard solution is only as accurate as the mass weighed and the volume of the flask; the concentration is calculated, not measured.<\/p>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: When the Solid Is Not Pure<\/h2>\n<p>Decide what damp pellets do to the concentration the student calculates.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-515\" class=\"h5p-iframe\" data-content-id=\"515\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Standard Solutions MCQ: Weighing Out a Solid That Has Taken Up Water\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">2<\/div>\n<h2>Preparing the Standard Solution<\/h2>\n<\/div>\n<ol>\n<li><strong>Weigh<\/strong> the solid accurately by difference into a clean beaker (for 0.100 mol dm\u207b\u00b3 Na\u2082CO\u2083 in 250 cm\u00b3: 0.0250 mol \u00d7 106.0 = 2.65 g).<\/li>\n<li><strong>Dissolve<\/strong> in a small volume of distilled water, stirring with a glass rod until no solid remains.<\/li>\n<li><strong>Transfer<\/strong> the solution to a 250 cm\u00b3 volumetric flask through a funnel, then <strong>rinse<\/strong> the beaker, rod and funnel with distilled water into the flask so that no solute is left behind.<\/li>\n<li><strong>Make up to the mark<\/strong> with distilled water, adding the last few cm\u00b3 dropwise until the bottom of the meniscus sits on the line at eye level.<\/li>\n<li><strong>Stopper and invert<\/strong> the flask several times to mix; the concentration is not uniform until you do.<\/li>\n<\/ol>\n<div class=\"ols-zoom-card\">\n<div class=\"ols-zoom-card-image\">\n<a class=\"ols-lightbox-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/wave-16.jpg\" aria-label=\"Open image full screen\">\n<img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/wave-16.jpg\" alt=\"Five-step strip for preparing a 250 cm\u00b3 standard solution: weigh 2.65 g, dissolve, transfer and rinse, make up to the mark, mix\">\n<\/a>\n<\/div>\n<div class=\"ols-zoom-card-caption\"><p>Every rinsing goes into the flask: the solute must all end up in the 250 cm\u00b3.<\/p><\/div>\n<\/div>\n<div class=\"ols-key-box\">\n<p><strong>Exam sentence:<\/strong> Rinse the beaker into the volumetric flask so that all the solute is transferred, make up to the mark with distilled water and invert to mix.<\/p>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: What Do You Weigh Out?<\/h2>\n<p>Work each one out on paper, then type the number.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-765\" class=\"h5p-iframe\" data-content-id=\"765\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Standard Solutions Flashcards: Mass, Moles and Concentration\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card purple\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">3<\/div>\n<h2>Carrying Out the Titration<\/h2>\n<\/div>\n<ol>\n<li><strong>Rinse<\/strong> the burette with the solution it will contain and the pipette with the solution it will measure. Rinse the conical flask with distilled water only.<\/li>\n<li><strong>Fill the burette<\/strong> using a funnel, remove the funnel, run solution through the tap to fill the jet, and read the initial volume at eye level to 0.05 cm\u00b3.<\/li>\n<li><strong>Pipette<\/strong> 25.0 cm\u00b3 of the other solution into the conical flask, letting it drain and touching the tip on the liquid surface; never blow out the last drop.<\/li>\n<li>Add two or three drops of a suitable <strong>indicator<\/strong>.<\/li>\n<li>Do a <strong>rough titration<\/strong> quickly to find the approximate end point, swirling the flask on a white tile.<\/li>\n<li>Repeat <strong>accurately<\/strong>, adding dropwise near the end point and rinsing the flask walls with distilled water, until you have at least two <strong>concordant<\/strong> titres within 0.10 cm\u00b3.<\/li>\n<\/ol>\n<div class=\"ols-zoom-card\">\n<div class=\"ols-zoom-card-image\">\n<a class=\"ols-lightbox-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/wave-17.jpg\" aria-label=\"Open image full screen\">\n<img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/wave-17.jpg\" alt=\"Titration technique: clamped burette over a swirled conical flask on a white tile, with pipette and methyl orange end point insets\">\n<\/a>\n<\/div>\n<div class=\"ols-zoom-card-caption\"><p>Dropwise addition near the end point and a white tile under the flask make the colour change sharp and easy to see.<\/p><\/div>\n<\/div>\n<div class=\"ols-key-box\">\n<p><strong>Key idea:<\/strong> The rough titre finds the end point quickly; the accurate titres, added dropwise at the end, give the concordant results used in the calculation.<\/p>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: The Order of an Accurate Titration<\/h2>\n<p>Drag the steps into the order they have to be done in.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-514\" class=\"h5p-iframe\" data-content-id=\"514\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Titration Technique Put in Order: One Accurate Titration\"><\/iframe><\/div><\/div>\n<\/section>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: What Does the Slip Do to the Titre?<\/h2>\n<p>For each slip, decide whether the recorded titre comes out larger, smaller or unchanged.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-516\" class=\"h5p-iframe\" data-content-id=\"516\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Titration Slips Quick Fire: Larger, Smaller or Unchanged\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card orange\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">4<\/div>\n<h2>Choosing the Indicator<\/h2>\n<\/div>\n<p>The indicator must change colour sharply at the equivalence point of the particular acid and base.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Indicator<\/th><th>Colour in acid<\/th><th>Colour in alkali<\/th><th>Suitable for<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>Methyl orange<\/strong><\/td><td>Red<\/td><td>Yellow<\/td><td>Strong acid with strong or weak base<\/td><\/tr>\n<tr><td><strong>Phenolphthalein<\/strong><\/td><td>Colourless<\/td><td>Pink<\/td><td>Strong base with strong or weak acid<\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>Universal indicator is never used: its gradual colour change gives no sharp end point. Use the minimum number of drops, because indicators are themselves weak acids or bases and consume a little of the reagent.<\/p>\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: Pick the Indicator<\/h2>\n<p>Choose the indicator and give the colour change as the flask would show it.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-517\" class=\"h5p-iframe\" data-content-id=\"517\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Titration Technique MCQ: Choosing an Indicator for a Weak Base\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">5<\/div>\n<h2>Common Exam Mistakes<\/h2>\n<\/div>\n<ul>\n<li>Rinsing the burette or pipette with water, which dilutes the solution and changes the titre.<\/li>\n<li>Leaving the funnel in the burette, so drips change the reading.<\/li>\n<li>Reading the burette from above or below eye level (parallax).<\/li>\n<li>Stopping after one accurate titre; concordant results are required.<\/li>\n<li>Choosing universal indicator.<\/li>\n<\/ul>\n<div class=\"ols-key-box\">\n<p><strong>Exam sentence:<\/strong> Rinse the burette with the solution it will hold, remove the funnel, read at eye level to 0.05 cm\u00b3, add dropwise near the end point and repeat until concordant.<\/p>\n<\/div>\n<\/article>\n\n<section class=\"ols-related-card\">\n        <h2>Related Topics<\/h2>\n        <p>Continue through this section by linking this page to equations, formulae and mole calculation revision.<\/p>\n        <div class=\"ols-related-grid\">\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-2-compounds-formulae-and-equations\/equations-and-reaction-types\/\">Equations and Reaction Types<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-2-compounds-formulae-and-equations\/equations-and-reaction-types\/writing-chemical-equations\/\">Writing Chemical Equations<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-3-amount-of-substance\/mole-calculations\/\">Mole Calculations<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-3-amount-of-substance\/empirical-and-molecular-formulae\/\">Empirical and Molecular Formulae<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-3-amount-of-substance\/calculations-with-solutions-and-gases\/\">Calculations with Solutions and Gases<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/2-1-1-atomic-structure-and-isotopes\/\">Atomic Structure &amp; The Periodic Table<\/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. 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