{"id":4757,"date":"2026-06-02T07:46:59","date_gmt":"2026-06-02T06:46:59","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/risks-hazards-and-practical-precautions\/"},"modified":"2026-10-23T18:46:00","modified_gmt":"2026-10-23T17:46:00","slug":"risks-hazards-and-practical-precautions","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/risks-hazards-and-practical-precautions\/","title":{"rendered":"Risks, Hazards and Practical Precautions"},"content":{"rendered":"\n<!--\n===============================================================================\nONLINE LEARNING SYSTEM COPYRIGHT NOTICE\n\u00a9 Online Learning System. 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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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matched.setAttribute('aria-current', 'page');\r\n          matched.setAttribute('tabindex', '-1');\r\n          matched.setAttribute('data-ols-disabled-parent', '1');\r\n        }\r\n      }\r\n    }\r\n\r\n    return true;\r\n  }\r\n\r\n  if (!highlightActive()) {\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\/edexcel\/\">Edexcel<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/\">Topic 5 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\/risks-hazards-and-practical-precautions\/\">Safety<\/a> \/\n        <span>Hazard &amp; Risk<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Hazard &amp; Risk<\/h1>\n        <p class=\"ols-page-intro\">A concise Edexcel A Level Chemistry revision guide to the difference between hazards and risks in practical chemistry, including common laboratory hazards and how risk can be reduced during experiments.<\/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      <\/header>\n\n      <article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">1<\/div>\n<h2>Before You Start<\/h2>\n<\/div>\n<p>This page builds on GCSE practical safety and hazard symbols.<\/p>\n<ul class=\"ols-list\">\n<li>Hazard symbols warn that a substance is toxic, flammable, corrosive or oxidising.<\/li>\n<li>Eye protection is worn whenever chemicals are mixed or heated.<\/li>\n<li>Flammable liquids are kept away from naked flames.<\/li>\n<li>A fume cupboard removes toxic gases and vapours from the room.<\/li>\n<\/ul>\n<\/article>\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: Hazard Pictograms<\/h2>\n<p>Four quick GCSE questions on hazard pictograms and risk assessments before you meet the A Level definitions.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"1277\"><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">2<\/div>\n          <h2>What Is a Hazard?<\/h2>\n        <\/div>\n\n        <p>A <strong>hazard<\/strong> is a substance or procedure that has the <strong>potential to cause harm<\/strong>.<\/p>\n        <p>In chemistry, a hazard might be linked to a chemical substance, a piece of apparatus, a flame, a sharp object, a hot surface, pressure build-up or a practical procedure.<\/p>\n\n        <div class=\"ols-definition-box\">\n          <p><strong>Definition:<\/strong> A hazard is something that could cause harm. It describes the possible danger before considering how likely that harm is to happen.<\/p>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n<div class=\"ols-figure-image\"><img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/fix-39.jpg\" alt=\"Flat vector panel showing common laboratory hazards with correct GHS pictograms and labels\"><\/div>\n<div class=\"ols-figure-caption\"><p>Hazards may come from the chemical itself, such as toxicity or flammability, or from how the substance or equipment is used.<\/p><\/div>\n<\/div>\n      <\/article>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">3<\/div>\n          <h2>Common Laboratory Hazards<\/h2>\n        <\/div>\n\n        <p>Laboratory chemicals are often labelled according to the type of hazard they present. These labels help students and teachers decide what precautions are needed before practical work begins.<\/p>\n        <p>Labels also warn that a substance is <strong>explosive<\/strong>, a longer-term <strong>health hazard<\/strong> or <strong>dangerous for the environment<\/strong>. Harmful and irritant share one pictogram, so read the wording on the bottle as well as the symbol.<\/p>\n\n        <div class=\"ols-hazard-grid\">\n          <div class=\"ols-hazard-pill\"><strong>Toxic<\/strong><span>Can cause serious harm if swallowed, inhaled or absorbed through the skin.<\/span><\/div>\n          <div class=\"ols-hazard-pill\"><strong>Flammable<\/strong><span>Can catch fire easily, especially near naked flames or sparks.<\/span><\/div>\n          <div class=\"ols-hazard-pill\"><strong>Harmful<\/strong><span>Can cause damage to health, but is usually less severe than toxic substances.<\/span><\/div>\n          <div class=\"ols-hazard-pill\"><strong>Irritant<\/strong><span>Can cause redness, itching or inflammation, especially on skin or in eyes.<\/span><\/div>\n          <div class=\"ols-hazard-pill\"><strong>Corrosive<\/strong><span>Can attack and destroy living tissue or damage materials.<\/span><\/div>\n          <div class=\"ols-hazard-pill\"><strong>Oxidising<\/strong><span>Can make other substances burn more easily by supplying oxygen or supporting oxidation.<\/span><\/div>\n          <div class=\"ols-hazard-pill\"><strong>Carcinogenic<\/strong><span>May increase the risk of cancer after exposure.<\/span><\/div>\n        <\/div>\n\n        <div class=\"ols-warning-box\">\n          <p><strong>Important:<\/strong> The hazard describes the potential for harm. It does not automatically tell you how likely harm is under the exact practical conditions used.<\/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: Which Hazard Is It?<\/h2>\n<p>Read each description and choose the hazard label that fits.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-60\" class=\"h5p-iframe\" data-content-id=\"60\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Hazard and Risk Quick Fire: Which Hazard Is Described?\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">4<\/div>\n          <h2>What Is Risk?<\/h2>\n        <\/div>\n\n        <p><strong>Risk<\/strong> is the <strong>likelihood<\/strong> that harm will occur as a result of using a hazardous substance or carrying out a procedure, together with how <strong>severe<\/strong> that harm would be. A risk assessment judges both.<\/p>\n        <p>This means a hazardous substance can sometimes pose a lower risk if it is used in a <strong>low concentration<\/strong>, in a <strong>small amount<\/strong>, or with suitable safety precautions.<\/p>\n\n        <div class=\"ols-definition-box\">\n          <p><strong>Definition:<\/strong> Risk describes how likely harm is to occur in a specific situation, and how serious that harm would be. It depends on the hazard, the quantity, the concentration, the method and the precautions used.<\/p>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n<div class=\"ols-figure-image\"><img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/fix-40.jpg\" alt=\"Flat vector panel: the same hazard at high and low risk, plus the precautions that lower risk\"><\/div>\n<div class=\"ols-figure-caption\"><p>Risk is reduced by controlling how hazardous substances are handled, stored and used during practical work.<\/p><\/div>\n<\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Same Chemical, Different Risk<\/h2>\n<p>Decide what is the same and what is different for the two students.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-61\" class=\"h5p-iframe\" data-content-id=\"61\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Hazard and Risk MCQ: Same Bromine Water, Different Risk\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card green\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">5<\/div>\n          <h2>Hazard Compared with Risk<\/h2>\n        <\/div>\n\n        <p>Students often confuse hazard and risk. A hazard is the possible source of harm. Risk is the chance that the harm will actually happen under the conditions used.<\/p>\n\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>Example in the laboratory<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Term\"><strong>Hazard<\/strong><\/td>\n                <td data-label=\"Meaning\">A substance or procedure with the potential to cause harm.<\/td>\n                <td data-label=\"Example in the laboratory\">Concentrated acid is corrosive because it can damage living tissue.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Term\"><strong>Risk<\/strong><\/td>\n                <td data-label=\"Meaning\">The likelihood that harm will occur in a particular situation.<\/td>\n                <td data-label=\"Example in the laboratory\">The risk is lower if dilute acid is used in small amounts while wearing eye protection.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Exam focus:<\/strong> If a question asks how to reduce risk, give a practical control measure, not just the name of the hazard.<\/p>\n          <p><strong>Common mistake:<\/strong> Diluting the acid does lower the risk, but it also changes the hazard, because dilute acid is an irritant rather than corrosive.<\/p>\n        <p>To show the difference between hazard and risk, keep the same substance and change only the amount, the apparatus or the surroundings.<\/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: Explain Hazard and Risk<\/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-689\" class=\"h5p-iframe\" data-content-id=\"689\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Hazard and Risk Explain: Is the Sodium Demonstration Too Risky?\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card yellow\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">6<\/div>\n          <h2>How Risks Can Be Reduced<\/h2>\n        <\/div>\n\n        <p>Risks can be reduced by changing the scale of the experiment, changing the method or using precautions specific to the hazard.<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Method of reducing risk<\/th>\n                <th>What this means<\/th>\n                <th>Why it works<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Method of reducing risk\"><strong>Work on a smaller scale<\/strong><\/td>\n                <td data-label=\"What this means\">Use smaller amounts of the hazardous substance.<\/td>\n                <td data-label=\"Why it works\">Less material is available to spill, burn, react or release harmful vapour.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Method of reducing risk\"><strong>Use specific precautions<\/strong><\/td>\n                <td data-label=\"What this means\">Choose safety measures that match the hazard.<\/td>\n                <td data-label=\"Why it works\">The control measure directly reduces the chance of harm from that particular hazard.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Method of reducing risk\"><strong>Use an alternative method<\/strong><\/td>\n                <td data-label=\"What this means\">Use a safer procedure or less hazardous substance where possible.<\/td>\n                <td data-label=\"Why it works\">Replacing the hazard, or reducing its severity, reduces the overall risk.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Hazard type<\/th>\n                <th>Suitable precaution<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Hazard type\"><strong>Irritant substances<\/strong><\/td>\n                <td data-label=\"Suitable precaution\">Wear safety goggles, especially when using dilute acids and alkalis.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Hazard type\"><strong>Corrosive substances<\/strong><\/td>\n                <td data-label=\"Suitable precaution\">Wear goggles and gloves when handling <strong>concentrated<\/strong> acids and alkalis, use the lowest concentration that works and keep the volumes small.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Hazard type\"><strong>Flammable substances<\/strong><\/td>\n                <td data-label=\"Suitable precaution\">Keep away from naked flames.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Hazard type\"><strong>Toxic substances<\/strong><\/td>\n                <td data-label=\"Suitable precaution\">Wear gloves, avoid skin contact and wash hands after use.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Hazard type\"><strong>Toxic or harmful gases and vapours<\/strong><\/td>\n                <td data-label=\"Suitable precaution\">Work in a <strong>fume cupboard<\/strong>, or in a well-ventilated room, so the gas is drawn away and not breathed in.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Hazard type\"><strong>Oxidising substances<\/strong><\/td>\n                <td data-label=\"Suitable precaution\">Keep away from flammable or easily oxidised materials.<\/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: Choose the Control Measure<\/h2>\n<p>For each practical situation, choose the control measure that matches the hazard.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"62\"><\/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: Hazard or Risk?<\/h2>\n<p>In each round, choose the one statement that uses the words hazard and risk correctly.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-63\" class=\"h5p-iframe\" data-content-id=\"63\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Hazard and Risk Summary: Telling Hazard from Risk\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">7<\/div>\n          <h2>Common Exam Mistakes<\/h2>\n        <\/div>\n\n        <ul>\n          <li>Do not define hazard as the chance of harm. That is <strong>risk<\/strong>.<\/li>\n          <li>Do not define risk as simply \u201cdanger\u201d. Risk is the <strong>likelihood<\/strong> that harm will occur, and how <strong>severe<\/strong> that harm would be.<\/li>\n          <li>Do not give vague precautions such as \u201cbe careful\u201d. Give a specific safety measure linked to the hazard.<\/li>\n          <li>Do not assume a hazardous chemical always has high risk. Concentration, amount and precautions affect risk.<\/li>\n        <\/ul>\n      <\/article>\n\n      \n\n      <section class=\"ols-faq-card\">\n<h2>FAQs<\/h2>\n<p>These questions secure the hazard and risk wording that examiners reward.<\/p>\n<div class=\"ols-faq-list\">\n<div class=\"ols-faq-item\">\n<h3>Is a hazard the same as a risk?<\/h3>\n<p>No. A hazard is anything with the potential to cause harm, such as a corrosive acid. Risk is how likely that harm is under the conditions used, and how severe it would be.<\/p>\n<\/div>\n<div class=\"ols-faq-item\">\n<h3>Do safety goggles reduce the hazard?<\/h3>\n<p>No. Goggles reduce the risk. The acid is just as corrosive; the precaution only makes harm to the eyes less likely.<\/p>\n<\/div>\n<div class=\"ols-faq-item\">\n<h3>Why is &#8220;be careful&#8221; not accepted as a precaution?<\/h3>\n<p>It names no action. Give a specific control linked to the hazard, such as a fume cupboard for a toxic gas or keeping a flammable liquid away from naked flames.<\/p>\n<\/div>\n<div class=\"ols-faq-item\">\n<h3>When must a fume cupboard be used?<\/h3>\n<p>Use one whenever a toxic or harmful gas or vapour is made or used, such as chlorine, sulfur dioxide or bromine. The fan draws the gas away from your breathing zone.<\/p>\n<\/div>\n<div class=\"ols-faq-item\">\n<h3>How does working on a smaller scale reduce risk?<\/h3>\n<p>Less of the hazardous substance is present, so a spill, fire or release of vapour is smaller and easier to control. The hazard itself is unchanged.<\/p>\n<\/div>\n<\/div>\n<\/section>\n\n      <!-- author card (moved to the end, 10 Oct 2026) -->\n      <div class=\"ols-author\">\n          <img decoding=\"async\"\n            class=\"ols-author-avatar-img\"\n            src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Author-Profile.jpeg\"\n            alt=\"Dr. Mohammed Al-Fatah\"\n          >\n\n          <div class=\"ols-author-content\">\n            <h2 class=\"ols-author-title\">Written by: Dr. Mohammed Al-Fatah<\/h2>\n            <p class=\"ols-author-description\">Chemistry specialist revision notes for A Level Chemistry.<\/p>\n\n            <a\n              class=\"ols-linkedin-pill\"\n              href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\"\n              target=\"_blank\"\n              rel=\"noopener noreferrer\"\n            >\n              <svg class=\"ols-linkedin-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\">\n                <path d=\"M4.98 3.5C4.98 4.88 3.86 6 2.48 6S0 4.88 0 3.5 1.12 1 2.48 1s2.5 1.12 2.5 2.5zM.5 8h4V24h-4V8zm7 0h3.8v2.2h.1c.5-.9 1.8-2.2 3.9-2.2 4.2 0 5 2.8 5 6.4V24h-4v-7.6c0-1.8 0-4.2-2.6-4.2s-3 2-3 4v7.8h-4V8z\"\/>\n              <\/svg>\n              View LinkedIn Profile\n            <\/a>\n          <\/div>\n        <\/div>\n\n\n      <section class=\"ols-related-card\">\n        <h2>Related Topic 5 Revision Notes<\/h2>\n        <p>Continue through Edexcel Topic 5 by linking practical safety to core quantitative chemistry and laboratory calculations.<\/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\/\">Mole Calculations<\/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 and Gases<\/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 and Molecular Formulae<\/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-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\/concentrations-of-solutions\/\">Concentrations of 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\/\">Topic 5 Overview<\/a>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-attribution-card ols-attr-std\" aria-label=\"Copyright notice\">\n<style id=\"ols-attribution-card-css\">.ols-attribution-card.ols-attr-std{background:linear-gradient(135deg,#ffffff,#f8fbff);border:1px solid rgba(28,36,75,0.14);border-radius:28px;box-shadow:0 18px 45px rgba(28,36,75,0.10);padding:34px;margin:24px 0;overflow:hidden;font-family:Poppins,Arial,sans-serif;box-sizing:border-box}.ols-attribution-card.ols-attr-std *{box-sizing:border-box}.ols-attribution-card.ols-attr-std p{margin:0;font-size:14px;line-height:1.65;font-weight:300;color:#667085}.ols-attribution-card.ols-attr-std strong{font-weight:700;color:#1C244B}@media (max-width:760px){.ols-attribution-card.ols-attr-std{padding:24px 18px;border-radius:22px}}<\/style>\n<p><strong>Copyright notice:<\/strong> This OLS revision content, including the explanations, layout, diagrams, tables and embedded learning structure, is authored for Online Learning System by Dr. Mohammed Al-Fatah. It may not be copied, reproduced, redistributed or adapted without written permission.<\/p>\n<\/section>\n    <\/main>\n  <\/div>\n<\/section>\n\n<script type=\"application\/ld+json\">\n{\n    \"@context\": \"https:\/\/schema.org\",\n    \"@graph\": [\n        {\n            \"@type\": \"WebPage\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/risks-hazards-and-practical-precautions\/hazard-and-risk\/#webpage\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/risks-hazards-and-practical-precautions\/hazard-and-risk\/\",\n            \"name\": \"Hazard & Risk - Edexcel A Level Chemistry Revision Notes\",\n            \"headline\": \"Hazard & Risk\",\n            \"description\": \"A concise Edexcel A Level Chemistry revision guide to hazards, risks, 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