{"id":12493,"date":"2026-10-03T08:33:11","date_gmt":"2026-10-03T07:33:11","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/"},"modified":"2026-10-03T08:36:12","modified_gmt":"2026-10-03T07:36:12","slug":"3-1-8-thermodynamics","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/","title":{"rendered":"3.1.8 Thermodynamics"},"content":{"rendered":"\n<div class=\"ols-aqa318-page\">\n\n  <aside class=\"ols-sidebar\">\n  <div class=\"ols-sidebar-header\">\n    <h3>Revision Notes<\/h3>\n    <p>A Level Chemistry<\/p>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>3.1.8 Thermodynamics<\/h4>\n\n    <ul class=\"ols-topic-list\">\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/\">3.1.8 Thermodynamics Overview<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/lattice-energy-and-born-haber-cycles\/\">Lattice Enthalpy and Born\u2013Haber Cycles<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/lattice-energy-trends-and-covalent-character\/\">Lattice Enthalpy Trends and Covalent Character<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/enthalpy-of-solution-and-hydration\/\">Enthalpy of Solution and Hydration<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/entropy-and-the-direction-of-change\/\">Entropy and the Direction of Change<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/calculating-entropy-changes\/\">Calculating Entropy Changes<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/feasibility-gibbs-energy-and-temperature\/\">Feasibility, Gibbs Energy and Temperature<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/thermodynamic-and-kinetic-stability\/\">Thermodynamic and Kinetic Stability<\/a>\n      <\/li>\n    <\/ul>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>Other Sections<\/h4>\n\n    <ul class=\"ols-topic-list\">\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-4-energetics\/\">3.1.4 Energetics<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-9-rate-equations\/\">3.1.9 Rate Equations<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-2-2-group-2-the-alkaline-earth-metals\/\">3.2.2 Group 2<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/required-practicals\/\">Required Practicals<\/a>\n      <\/li>\n    <\/ul>\n  <\/div>\n<\/aside>\n\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 = 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rgba(255,255,255,0.46), transparent 24%), linear-gradient(135deg, #f0fdf4 0%, #86efac 45%, #166534 100%); }\n    .ols-aqa318-visual--hi { background: radial-gradient(circle at 24% 18%, rgba(255,255,255,0.46), transparent 24%), linear-gradient(135deg, #fdf4ff 0%, #d8b4fe 45%, #7e22ce 100%); }\n    .ols-aqa318-visual--ca { background: radial-gradient(circle at 24% 18%, rgba(255,255,255,0.46), transparent 24%), linear-gradient(135deg, #fff7ed 0%, #fb923c 45%, #9a3412 100%); }\n    .ols-aqa318-visual--de { background: radial-gradient(circle at 24% 18%, rgba(255,255,255,0.46), transparent 24%), linear-gradient(135deg, #eef2ff 0%, #818cf8 45%, #3730a3 100%); }\n    .ols-aqa318-visual--lc { background: radial-gradient(circle at 24% 18%, rgba(255,255,255,0.46), transparent 24%), linear-gradient(135deg, #ecfeff 0%, #22d3ee 45%, #0e7490 100%); }\n    .ols-aqa318-visual--ei { background: radial-gradient(circle at 24% 18%, rgba(255,255,255,0.46), transparent 24%), linear-gradient(135deg, #f5f3ff 0%, #a78bfa 45%, #5b21b6 100%); }\n    .ols-aqa318-visual--kc { background: radial-gradient(circle at 24% 18%, rgba(255,255,255,0.46), transparent 24%), linear-gradient(135deg, #f0fdf4 0%, #4ade80 45%, #166534 100%); }\n  <\/style>\n\n  <!-- BREADCRUMB BAR -->\n  <div class=\"ols-aqa318-breadcrumb-bar\">\n    <div class=\"ols-aqa318-container\">\n      <nav class=\"ols-aqa318-breadcrumb\" 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\/aqa\/\">AQA<\/a> \/\n          <span>3.1.8 Thermodynamics<\/span>\n        <\/nav>\n    <\/div>\n  <\/div>\n\n  <!-- INTRO -->\n  <section class=\"ols-aqa318-intro\">\n    <div class=\"ols-aqa318-container\">\n      <div class=\"ols-aqa318-intro-inner\">\n        <div>\n          <div class=\"ols-aqa318-eyebrow\">AQA A Level Chemistry<\/div>\n          <h1>3.1.8<br>Thermodynamics<\/h1>\n          <div class=\"ols-aqa318-accent-bar\"><\/div>\n          <p class=\"ols-aqa318-intro-lead\">Section 3.1.8 covers Born\u2013Haber cycles (both definitions of lattice enthalpy, the enthalpy changes of formation, atomisation, ionisation, bond dissociation and electron affinity, constructing and using cycles, the perfect ionic model as evidence for covalent character, hydration and solution cycles) and Gibbs free-energy change and entropy change (why \u0394H alone is not enough, entropy and disorder, \u0394G = \u0394H \u2212 T\u0394S, \u0394G \u2264 0 for feasibility, entropy changes from absolute entropies, how \u0394G varies with temperature and the temperature at which a reaction becomes feasible).<\/p>\n        <\/div>\n        <div class=\"ols-aqa318-info-grid\">\n          <div class=\"ols-aqa318-info-card\"><div class=\"ols-aqa318-info-card-label\">Exam Paper<\/div><div class=\"ols-aqa318-info-card-value\">Paper 1<\/div><div class=\"ols-aqa318-info-card-sub\">7405\/1 (and Paper 3)<\/div><\/div>\n          <div class=\"ols-aqa318-info-card\"><div class=\"ols-aqa318-info-card-label\">Specification Points<\/div><div class=\"ols-aqa318-info-card-value\">3.1.8.1 &#8211; 3.1.8.2<\/div><div class=\"ols-aqa318-info-card-sub\">2 sections covered<\/div><\/div>\n          <div class=\"ols-aqa318-info-card\"><div class=\"ols-aqa318-info-card-label\">Topic Parts<\/div><div class=\"ols-aqa318-info-card-value\">7 pages<\/div><div class=\"ols-aqa318-info-card-sub\">Revision notes available<\/div><\/div>\n          <div class=\"ols-aqa318-info-card\"><div class=\"ols-aqa318-info-card-label\">Exam Board<\/div><div class=\"ols-aqa318-info-card-value\">AQA<\/div><div class=\"ols-aqa318-info-card-sub\">7405 (2015 onwards)<\/div><\/div>\n        <\/div>\n      <\/div>\n    <\/div>\n  <\/section>\n\n  <!-- TOPIC CARDS -->\n  <section class=\"ols-aqa318-topics\">\n    <div class=\"ols-aqa318-container\">\n      <div class=\"ols-aqa318-section-header\">\n        <h2 class=\"ols-aqa318-section-title\">Revision Notes<\/h2>\n        <p class=\"ols-aqa318-section-sub\">Work through 3.1.8 Thermodynamics in a structured sequence.<\/p>\n      <\/div>\n      <div class=\"ols-aqa318-cards-grid\">\n\n        <!-- Card 1: w => `${lattC(w)} and Born\u2013Haber Cycles` -->\n        <a class=\"ols-aqa318-card ols-aqa318-card--available\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/lattice-energy-and-born-haber-cycles\/\">\n          <div class=\"ols-aqa318-card-img-wrap\">\n            <div class=\"ols-aqa318-visual ols-aqa318-visual--de\">\n              <div class=\"ols-aqa318-visual-panel\">\n                <div class=\"ols-aqa318-visual-kicker\">Hess\u2019s law for ionic solids<\/div>\n                <div class=\"ols-aqa318-visual-main\">Born\u2013Haber<br>Cycles<\/div>\n                <div class=\"ols-aqa318-config-line\" aria-hidden=\"true\"><span>lattice enthalpy, \u0394atH, electron affinity<\/span><\/div>\n              <\/div>\n            <\/div>\n            <div class=\"ols-aqa318-card-num\">1<\/div>\n            <span class=\"ols-aqa318-card-status ols-aqa318-card-status--available\">Available<\/span>\n          <\/div>\n          <div class=\"ols-aqa318-card-body\">\n            <p class=\"ols-aqa318-card-title\">Lattice Enthalpy and Born\u2013Haber Cycles<\/p>\n            <p class=\"ols-aqa318-card-desc\">Lattice enthalpy and Born\u2013Haber cycles: definitions of atomisation, ionisation energy and electron affinity, constructing the cycle for NaCl and MgCl\u2082 and calculating the missing value.<\/p>\n            <span class=\"ols-aqa318-card-cta\">Start revising<svg viewBox=\"0 0 16 16\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\" stroke-linejoin=\"round\"><path d=\"M3 8h10M9 4l4 4-4 4\"><\/path><\/svg><\/span>\n          <\/div>\n        <\/a>\n\n        <!-- Card 2: w => `${lattC(w)} Trends and Covalent Character` -->\n        <a class=\"ols-aqa318-card ols-aqa318-card--available\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/lattice-energy-trends-and-covalent-character\/\">\n          <div class=\"ols-aqa318-card-img-wrap\">\n            <div class=\"ols-aqa318-visual ols-aqa318-visual--lc\">\n              <div class=\"ols-aqa318-visual-panel\">\n                <div class=\"ols-aqa318-visual-kicker\">Charge density<\/div>\n                <div class=\"ols-aqa318-visual-main\">Polarisation and<br>Covalent Character<\/div>\n                <div class=\"ols-aqa318-config-line\" aria-hidden=\"true\"><span>theoretical against experimental<\/span><\/div>\n              <\/div>\n            <\/div>\n            <div class=\"ols-aqa318-card-num\">2<\/div>\n            <span class=\"ols-aqa318-card-status ols-aqa318-card-status--available\">Available<\/span>\n          <\/div>\n          <div class=\"ols-aqa318-card-body\">\n            <p class=\"ols-aqa318-card-title\">Lattice Enthalpy Trends and Covalent Character<\/p>\n            <p class=\"ols-aqa318-card-desc\">Lattice enthalpy trends: charge and radius, the perfect ionic model against Born\u2013Haber values, polarisation and covalent character in ionic compounds.<\/p>\n            <span class=\"ols-aqa318-card-cta\">Start revising<svg viewBox=\"0 0 16 16\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\" stroke-linejoin=\"round\"><path d=\"M3 8h10M9 4l4 4-4 4\"><\/path><\/svg><\/span>\n          <\/div>\n        <\/a>\n\n        <!-- Card 3: Enthalpy of Solution and Hydration -->\n        <a class=\"ols-aqa318-card ols-aqa318-card--available\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/enthalpy-of-solution-and-hydration\/\">\n          <div class=\"ols-aqa318-card-img-wrap\">\n            <div class=\"ols-aqa318-visual ols-aqa318-visual--ei\">\n              <div class=\"ols-aqa318-visual-panel\">\n                <div class=\"ols-aqa318-visual-kicker\">Lattice broken, ions hydrated<\/div>\n                <div class=\"ols-aqa318-visual-main\">Solution and<br>Hydration<\/div>\n                <div class=\"ols-aqa318-config-line\" aria-hidden=\"true\"><span>\u0394solH = \u2212LE + \u03a3\u0394hydH<\/span><\/div>\n              <\/div>\n            <\/div>\n            <div class=\"ols-aqa318-card-num\">3<\/div>\n            <span class=\"ols-aqa318-card-status ols-aqa318-card-status--available\">Available<\/span>\n          <\/div>\n          <div class=\"ols-aqa318-card-body\">\n            <p class=\"ols-aqa318-card-title\">Enthalpy of Solution and Hydration<\/p>\n            <p class=\"ols-aqa318-card-desc\">Enthalpy of solution and hydration: definitions, energy cycles with lattice enthalpy, worked calculations and the effect of ionic charge and radius.<\/p>\n            <span class=\"ols-aqa318-card-cta\">Start revising<svg viewBox=\"0 0 16 16\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\" stroke-linejoin=\"round\"><path d=\"M3 8h10M9 4l4 4-4 4\"><\/path><\/svg><\/span>\n          <\/div>\n        <\/a>\n\n        <!-- Card 4: Entropy and the Direction of Change -->\n        <a class=\"ols-aqa318-card ols-aqa318-card--available\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/entropy-and-the-direction-of-change\/\">\n          <div class=\"ols-aqa318-card-img-wrap\">\n            <div class=\"ols-aqa318-visual ols-aqa318-visual--ox\">\n              <div class=\"ols-aqa318-visual-panel\">\n                <div class=\"ols-aqa318-visual-kicker\">Disorder and dispersal<\/div>\n                <div class=\"ols-aqa318-visual-main\">Entropy<\/div>\n                <div class=\"ols-aqa318-config-line\" aria-hidden=\"true\"><span>S rises: solid, liquid, gas<\/span><\/div>\n              <\/div>\n            <\/div>\n            <div class=\"ols-aqa318-card-num\">4<\/div>\n            <span class=\"ols-aqa318-card-status ols-aqa318-card-status--available\">Available<\/span>\n          <\/div>\n          <div class=\"ols-aqa318-card-body\">\n            <p class=\"ols-aqa318-card-title\">Entropy and the Direction of Change<\/p>\n            <p class=\"ols-aqa318-card-desc\">Entropy: disorder and the dispersal of energy, entropy and temperature, changes of state, dissolving, gas moles and the natural direction of change.<\/p>\n            <span class=\"ols-aqa318-card-cta\">Start revising<svg viewBox=\"0 0 16 16\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\" stroke-linejoin=\"round\"><path d=\"M3 8h10M9 4l4 4-4 4\"><\/path><\/svg><\/span>\n          <\/div>\n        <\/a>\n\n        <!-- Card 5: Calculating Entropy Changes -->\n        <a class=\"ols-aqa318-card ols-aqa318-card--available\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/calculating-entropy-changes\/\">\n          <div class=\"ols-aqa318-card-img-wrap\">\n            <div class=\"ols-aqa318-visual ols-aqa318-visual--tc\">\n              <div class=\"ols-aqa318-visual-panel\">\n                <div class=\"ols-aqa318-visual-kicker\">\u03a3S(products) \u2212 \u03a3S(reactants)<\/div>\n                <div class=\"ols-aqa318-visual-main\">Entropy<br>Calculations<\/div>\n                <div class=\"ols-aqa318-config-line\" aria-hidden=\"true\"><span>J K\u207b\u00b9 mol\u207b\u00b9, sign and size<\/span><\/div>\n              <\/div>\n            <\/div>\n            <div class=\"ols-aqa318-card-num\">5<\/div>\n            <span class=\"ols-aqa318-card-status ols-aqa318-card-status--available\">Available<\/span>\n          <\/div>\n          <div class=\"ols-aqa318-card-body\">\n            <p class=\"ols-aqa318-card-title\">Calculating Entropy Changes<\/p>\n            <p class=\"ols-aqa318-card-desc\">Entropy calculations: \u0394S from standard entropies, units and worked examples.<\/p>\n            <span class=\"ols-aqa318-card-cta\">Start revising<svg viewBox=\"0 0 16 16\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\" stroke-linejoin=\"round\"><path d=\"M3 8h10M9 4l4 4-4 4\"><\/path><\/svg><\/span>\n          <\/div>\n        <\/a>\n\n        <!-- Card 6: Feasibility, Gibbs Energy and Temperature -->\n        <a class=\"ols-aqa318-card ols-aqa318-card--available\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/feasibility-gibbs-energy-and-temperature\/\">\n          <div class=\"ols-aqa318-card-img-wrap\">\n            <div class=\"ols-aqa318-visual ols-aqa318-visual--tr\">\n              <div class=\"ols-aqa318-visual-panel\">\n                <div class=\"ols-aqa318-visual-kicker\">\u0394G = \u0394H \u2212 T\u0394S<\/div>\n                <div class=\"ols-aqa318-visual-main\">Feasibility and<br>Temperature<\/div>\n                <div class=\"ols-aqa318-config-line\" aria-hidden=\"true\"><span>T = \u0394H \u00f7 \u0394S<\/span><\/div>\n              <\/div>\n            <\/div>\n            <div class=\"ols-aqa318-card-num\">6<\/div>\n            <span class=\"ols-aqa318-card-status ols-aqa318-card-status--available\">Available<\/span>\n          <\/div>\n          <div class=\"ols-aqa318-card-body\">\n            <p class=\"ols-aqa318-card-title\">Feasibility, Gibbs Energy and Temperature<\/p>\n            <p class=\"ols-aqa318-card-desc\">Feasibility: \u0394G = \u0394H \u2212 T\u0394S, the sign of \u0394G, the effect of temperature and the temperature at which a reaction becomes feasible.<\/p>\n            <span class=\"ols-aqa318-card-cta\">Start revising<svg viewBox=\"0 0 16 16\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\" stroke-linejoin=\"round\"><path d=\"M3 8h10M9 4l4 4-4 4\"><\/path><\/svg><\/span>\n          <\/div>\n        <\/a>\n\n        <!-- Card 7: Thermodynamic and Kinetic Stability -->\n        <a class=\"ols-aqa318-card ols-aqa318-card--available\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/thermodynamic-and-kinetic-stability\/\">\n          <div class=\"ols-aqa318-card-img-wrap\">\n            <div class=\"ols-aqa318-visual ols-aqa318-visual--ca\">\n              <div class=\"ols-aqa318-visual-panel\">\n                <div class=\"ols-aqa318-visual-kicker\">Feasible is not fast<\/div>\n                <div class=\"ols-aqa318-visual-main\">Thermodynamic and<br>Kinetic Stability<\/div>\n                <div class=\"ols-aqa318-config-line\" aria-hidden=\"true\"><span>\u0394G, E\u2090, diamond and petrol<\/span><\/div>\n              <\/div>\n            <\/div>\n            <div class=\"ols-aqa318-card-num\">7<\/div>\n            <span class=\"ols-aqa318-card-status ols-aqa318-card-status--available\">Available<\/span>\n          <\/div>\n          <div class=\"ols-aqa318-card-body\">\n            <p class=\"ols-aqa318-card-title\">Thermodynamic and Kinetic Stability<\/p>\n            <p class=\"ols-aqa318-card-desc\">Thermodynamic and kinetic stability: feasible but slow reactions, activation energy and the limits of \u0394G and \u0394Stotal predictions.<\/p>\n            <span class=\"ols-aqa318-card-cta\">Start revising<svg viewBox=\"0 0 16 16\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\" stroke-linejoin=\"round\"><path d=\"M3 8h10M9 4l4 4-4 4\"><\/path><\/svg><\/span>\n          <\/div>\n        <\/a>\n\n      <\/div>\n    <\/div>\n  <\/section>\n\n  <!-- SPECIFICATION -->\n  <section class=\"ols-aqa318-spec-section\">\n    <div class=\"ols-aqa318-container\">\n      <div class=\"ols-aqa318-spec-wrap\">\n        <div class=\"ols-aqa318-spec-pill\">Specification Coverage<\/div>\n        <h2 class=\"ols-aqa318-spec-heading\">3.1.8 Thermodynamics &#8211; AQA A Level Chemistry<\/h2>\n        <p class=\"ols-aqa318-spec-intro-text\">The following AQA specification points outline the knowledge and skills students are expected to demonstrate. Wording follows the AQA A Level Chemistry (7405) specification.<\/p>\n        <h3 class=\"ols-aqa318-spec-group-title\">3.1.8.1 Born\u2013Haber cycles<\/h3>\n        <div class=\"ols-aqa318-spec-rows\">\n          <div class=\"ols-aqa318-spec-row ols-aqa318-spec-row--light\"><div class=\"ols-aqa318-spec-code\">3.1.8.1<\/div><div class=\"ols-aqa318-spec-text\"><div class=\"ols-aqa318-spec-sub-list\"><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">i-a<\/div><div class=\"ols-aqa318-spec-sub-text\">know that lattice enthalpy can be defined as enthalpy of lattice dissociation<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">i-b<\/div><div class=\"ols-aqa318-spec-sub-text\">know that lattice enthalpy can be defined as enthalpy of lattice formation<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">ii-a<\/div><div class=\"ols-aqa318-spec-sub-text\">define enthalpy of formation<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">ii-b<\/div><div class=\"ols-aqa318-spec-sub-text\">define ionisation energy<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">ii-c<\/div><div class=\"ols-aqa318-spec-sub-text\">define enthalpy of atomisation<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">ii-d<\/div><div class=\"ols-aqa318-spec-sub-text\">define bond enthalpy<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">ii-e<\/div><div class=\"ols-aqa318-spec-sub-text\">define electron affinity<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">ii-f<\/div><div class=\"ols-aqa318-spec-sub-text\">define lattice enthalpy<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">iii<\/div><div class=\"ols-aqa318-spec-sub-text\">construct Born-Haber cycles to calculate lattice enthalpies using enthalpy of formation, ionisation energy, enthalpy of atomisation, bond enthalpy and electron affinity<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">iv<\/div><div class=\"ols-aqa318-spec-sub-text\">construct Born-Haber cycles to calculate one of the other enthalpy changes when lattice enthalpy is known<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">v<\/div><div class=\"ols-aqa318-spec-sub-text\">compare lattice enthalpies from Born-Haber cycles with those from calculations based on a perfect ionic model to provide evidence for covalent character in ionic compounds<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">vi<\/div><div class=\"ols-aqa318-spec-sub-text\">define the term enthalpy of hydration<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">vii<\/div><div class=\"ols-aqa318-spec-sub-text\">use cycles to calculate enthalpies of solution for ionic compounds from lattice enthalpies and enthalpies of hydration<\/div><\/div><\/div><\/div><\/div>\n        <\/div>\n\n        <h3 class=\"ols-aqa318-spec-group-title\">3.1.8.2 Gibbs free-energy change, \u0394G, and entropy change, \u0394S<\/h3>\n        <div class=\"ols-aqa318-spec-rows\">\n          <div class=\"ols-aqa318-spec-row ols-aqa318-spec-row--mid\"><div class=\"ols-aqa318-spec-code ols-aqa318-spec-code--mid\">3.1.8.2<\/div><div class=\"ols-aqa318-spec-text\"><div class=\"ols-aqa318-spec-sub-list\"><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">i<\/div><div class=\"ols-aqa318-spec-sub-text\">understand that DeltaH alone is not sufficient to explain feasible change<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">ii<\/div><div class=\"ols-aqa318-spec-sub-text\">understand the concept of increasing disorder (entropy change, DeltaS) and how it accounts for feasibility of change<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">iii-a<\/div><div class=\"ols-aqa318-spec-sub-text\">know the relationship DeltaG = DeltaH &#8211; TDeltaS<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">iv<\/div><div class=\"ols-aqa318-spec-sub-text\">know that for a reaction to be feasible, the value of DeltaG must be zero or negative<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">v<\/div><div class=\"ols-aqa318-spec-sub-text\">calculate entropy changes from absolute entropy values<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">vi<\/div><div class=\"ols-aqa318-spec-sub-text\">use DeltaG = DeltaH &#8211; TDeltaS to determine how DeltaG varies with temperature<\/div><\/div><div class=\"ols-aqa318-spec-sub-row\"><div class=\"ols-aqa318-spec-sub-code\">vii<\/div><div class=\"ols-aqa318-spec-sub-text\">use DeltaG = DeltaH &#8211; TDeltaS to determine the temperature at which a reaction becomes feasible<\/div><\/div><\/div><\/div><\/div>\n        <\/div>\n      <\/div>\n    <\/div>\n  <\/section>\n\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@graph\": [\n    {\n      \"@type\": \"CollectionPage\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/#webpage\",\n      \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-8-thermodynamics\/\",\n      \"name\": \"3.1.8 Thermodynamics | AQA A Level Chemistry | Online Learning System\",\n      \"description\": \"AQA A Level Chemistry 3.1.8 Thermodynamics revision notes: lattice enthalpy and born\u2013haber cycles, lattice 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