{"id":4819,"date":"2026-06-03T06:24:27","date_gmt":"2026-06-03T05:24:27","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/"},"modified":"2026-10-14T09:06:46","modified_gmt":"2026-10-14T08:06:46","slug":"carboxylic-acid","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/","title":{"rendered":"Carboxylic Acid"},"content":{"rendered":"\n<aside class=\"ols-sidebar\">\r\n  <div class=\"ols-sidebar-header\">\r\n    <h3>Revision Notes<\/h3>\r\n    <p>A Level Chemistry<\/p>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Topic 6 Organic Chemistry I<\/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-6-organic-chemistry-i\/introduction-to-organic-chemistry\/\">Introduction to Organic Chemistry<\/a>\r\n\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-6-organic-chemistry-i\/introduction-to-organic-chemistry\/iupac-rules\/\">IUPAC Rules<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/alkene\/\">Alkene<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/alcohol\/\">Alcohol<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/halogenoalkanes\/\">Halogenoalkanes<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/aldehyde\/\">Aldehyde<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/ketone\/\">Ketone<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/\">Carboxylic Acid<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/ester\/\">Ester<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/isomerism\/\">Isomerism<\/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-6-organic-chemistry-i\/alkanes\/\">Alkanes<\/a>\r\n\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-6-organic-chemistry-i\/alkanes\/crude-oil\/\">Alkanes from Crude Oil<\/a>\r\n\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-6-organic-chemistry-i\/alkanes\/crude-oil\/fractional-distillation\/\">Fractional Distillation<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/crude-oil\/cracking\/\">Cracking<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/crude-oil\/reforming\/\">Reforming<\/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-6-organic-chemistry-i\/alkanes\/fuel\/\">Alkanes as Fuel<\/a>\r\n\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-6-organic-chemistry-i\/alkanes\/fuel\/combustion\/\">Combustion<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/fuel\/oxides-of-sulfur\/\">Oxides of Sulfur<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/fuel\/oxides-of-nitrogen\/\">Oxides of Nitrogen<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/fuel\/catalytic-converter\/\">Catalytic Converter<\/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-6-organic-chemistry-i\/alkanes\/alternative-fuel\/\">Alternative Fuel<\/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-6-organic-chemistry-i\/alkanes\/reactions\/\">Reactions of Alkanes<\/a>\r\n\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-6-organic-chemistry-i\/alkanes\/reactions\/free-radical-substitution\/\">Free Radical Substitution<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/initiation\/\">Initiation<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/propagation\/\">Propagation<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/termination\/\">Termination<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/further-substitution\/\">Further Substitution<\/a>\r\n              <\/li>\r\n            <\/ul>\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-6-organic-chemistry-i\/alkenes\/\">Alkenes<\/a>\r\n\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-6-organic-chemistry-i\/alkenes\/alkene-bonding\/\">Alkene Bonding<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/geometric-isomerism\/\">Geometric Isomerism<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/electrophilic-addition-mechanism\/\">Electrophilic Addition Mechanism<\/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-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/\">Reactions of Alkenes<\/a>\r\n\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-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/halogens\/\">Halogens<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/hydrogen-halide\/\">Hydrogen Halide<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/bromine-water\/\">Bromine Water<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/hydrogen\/\">Hydrogen<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/steam\/\">Steam<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/kmno4\/\">KMnO4<\/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-6-organic-chemistry-i\/alkenes\/polymerisation-reactions\/\">Polymerisation Reactions<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/polymer-waste\/\">Polymer Waste<\/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-6-organic-chemistry-i\/halogenoalkanes\/\">Halogenoalkanes<\/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-6-organic-chemistry-i\/alcohols\/\">Alcohols<\/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-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-5-formulae-equations-and-amounts-of-substance\/\">Topic 5 Formulae, Equations &amp; Amounts<\/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    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      a.removeAttribute('data-ols-disabled-parent');\r\n    });\r\n\r\n    links.forEach(function(a) {\r\n      try {\r\n        var href = a.getAttribute('href');\r\n        if (!href || href === '#' || href.charAt(0) === '#') return;\r\n        var linkPath = normalisePath(new URL(href, window.location.origin).pathname);\r\n        if (!linkPath) return;\r\n        if (currentPath === linkPath || currentPath.indexOf(linkPath + '\/') === 0) {\r\n          if (linkPath.length > matchedLength) {\r\n            matched = a;\r\n            matchedLength = linkPath.length;\r\n          }\r\n        }\r\n      } catch(e) {}\r\n    });\r\n\r\n    if (matched) {\r\n      var matchedLi = matched.closest('li');\r\n      var parentSub = matched.closest('.ols-subtopic-list');\r\n\r\n      if (parentSub) {\r\n        if (matchedLi) {\r\n          matchedLi.classList.add('active');\r\n          matched.setAttribute('aria-current', 'page');\r\n        }\r\n\r\n        var parentLi = parentSub.closest('li');\r\n        while (parentLi) {\r\n          parentLi.classList.add('parent-active', 'active-main');\r\n\r\n          var parentLink = parentLi.querySelector(':scope > a');\r\n          if (parentLink) {\r\n            parentLink.setAttribute('aria-current', 'true');\r\n            parentLink.setAttribute('tabindex', '-1');\r\n            parentLink.setAttribute('data-ols-disabled-parent', '1');\r\n          }\r\n\r\n          var higherSub = parentLi.parentElement.closest('.ols-subtopic-list');\r\n          parentLi = higherSub ? higherSub.closest('li') : null;\r\n        }\r\n      } else {\r\n        if (matchedLi) {\r\n          matchedLi.classList.add('parent-active', 'active-main');\r\n          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<section class=\"ols-revision-page ols-carboxylic-acid-page\">\n  <style>\n    .ols-revision-page {\n      --navy: #1C244B;\n      --blue: #2563eb;\n      --soft-blue: #eef4ff;\n      --soft-red: #fff7f7;\n      --soft-purple: #f7f0ff;\n      --soft-green: #f0f7f1;\n      --soft-orange: #fff7ed;\n      --grey-text: #667085;\n      --body-text: #1f2937;\n      --border: rgba(28, 36, 75, 0.14);\n      --shadow: 0 18px 45px rgba(28, 36, 75, 0.10);\n      --inner-shadow: 0 10px 26px rgba(28, 36, 75, 0.08);\n      font-family: Poppins, Arial, sans-serif;\n      color: var(--navy);\n      background: #ffffff;\n    }\n\n    .ols-revision-page * { box-sizing: border-box; }\n    .ols-main { min-width: 0; max-width: 970px; }\n    .ols-breadcrumbs { display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0 22px; font-size: 15px; color: var(--grey-text); }\n    .ols-breadcrumbs a, .ols-breadcrumbs span { color: var(--grey-text); text-decoration: none; font-weight: 600; }\n    .ols-breadcrumbs a:hover { color: var(--blue); text-decoration: underline; text-underline-offset: 3px; }\n    .ols-title-card, .ols-note-card, .ols-h5p-card, .ols-related-card { background: #ffffff; border: 1px solid var(--border); border-radius: 28px; box-shadow: var(--shadow); padding: 34px; margin-bottom: 24px; overflow: hidden; }\n    .ols-title-card { background: linear-gradient(135deg, #ffffff 0%, #f8fbff 100%); }\n    .ols-title-card h1 { margin: 0 0 18px; font-size: clamp(36px, 5vw, 58px); line-height: 1.08; font-weight: 800; letter-spacing: -0.04em; color: #111827; }\n    .ols-page-intro { font-size: 19px; line-height: 1.7; font-weight: 300; color: var(--body-text); margin: 0 0 22px; }\n    .ols-badges { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 22px; }\n    .ols-badge { display: inline-flex; align-items: center; padding: 9px 14px; border-radius: 999px; background: #ffffff; border: 1px solid var(--border); font-size: 15px; font-weight: 600; color: var(--navy); }\n    .ols-author {\n      display:flex;\n      align-items:center;\n      gap:20px;\n      padding:28px;\n      border-radius:28px;\n      background:linear-gradient(135deg,#ffffff 0%,#f8fbff 100%);\n      border:1px solid rgba(28,36,75,0.12);\n      box-shadow:0 18px 45px rgba(28,36,75,0.10);\n    }\n\n    .ols-author-avatar-img {\n      width:92px;\n      height:92px;\n      border-radius:50%;\n      object-fit:cover;\n      object-position:center;\n      flex-shrink:0;\n      border:4px solid #ffffff;\n      box-shadow:\n        0 14px 32px rgba(28,36,75,0.18),\n        0 0 0 1px rgba(28,36,75,0.10);\n      transition:\n        transform 0.25s ease,\n        box-shadow 0.25s ease;\n    }\n\n    .ols-author:hover .ols-author-avatar-img {\n      transform:scale(1.04);\n      box-shadow:\n        0 20px 42px rgba(28,36,75,0.22),\n        0 0 0 1px rgba(28,36,75,0.10);\n    }\n\n    .ols-author-content {\n      min-width:0;\n    }\n\n    .ols-author-title {\n      margin:0 0 4px;\n      font-size:clamp(24px,3vw,34px);\n      line-height:1.15;\n      font-weight:700;\n      color:#1C244B;\n      letter-spacing:-0.03em;\n    }\n\n    .ols-author-description {\n      margin:0;\n      font-size:17px;\n      line-height:1.7;\n      font-weight:300;\n      color:#667085;\n    }\n\n    .ols-linkedin-pill {\n      display:inline-flex;\n      align-items:center;\n      justify-content:center;\n      gap:10px;\n      margin-top:16px;\n      padding:11px 18px;\n      border-radius:999px;\n      background:linear-gradient(135deg,#0A66C2,#004182);\n      color:#ffffff !important;\n      text-decoration:none;\n      font-size:14px;\n      line-height:1;\n      font-weight:700;\n      letter-spacing:0.01em;\n      box-shadow:0 10px 22px rgba(10,102,194,0.24);\n      position:relative;\n      overflow:hidden;\n      transition:\n        transform 0.22s ease,\n        box-shadow 0.22s ease;\n    }\n\n    .ols-linkedin-pill::before {\n      content:\"\";\n      position:absolute;\n      top:0;\n      left:-120%;\n      width:100%;\n      height:100%;\n      background:linear-gradient(\n        120deg,\n        rgba(255,255,255,0) 0%,\n        rgba(255,255,255,0.28) 50%,\n        rgba(255,255,255,0) 100%\n      );\n      transition:left 0.7s ease;\n    }\n\n    .ols-linkedin-pill:hover {\n      transform:translateY(-3px) scale(1.03);\n      color:#ffffff !important;\n      box-shadow:\n        0 16px 34px rgba(10,102,194,0.34),\n        0 0 0 6px rgba(10,102,194,0.10);\n    }\n\n    .ols-linkedin-pill:hover::before {\n      left:120%;\n    }\n\n    .ols-linkedin-icon {\n      width:18px;\n      height:18px;\n      display:block;\n      flex-shrink:0;\n    }\n    .ols-note-card.soft { background: linear-gradient(135deg, #ffffff 0%, var(--soft-red) 100%); }\n    .ols-note-card.purple { background: linear-gradient(135deg, #ffffff 0%, var(--soft-purple) 100%); }\n    .ols-note-card.orange { background: linear-gradient(135deg, #ffffff 0%, var(--soft-orange) 100%); }\n    .ols-note-title { display: flex; align-items: center; gap: 14px; margin-bottom: 20px; }\n    .ols-note-icon { width: 52px; height: 52px; border-radius: 16px; background: var(--navy); color: #ffffff; display: grid; place-items: center; font-size: 24px; font-weight: 800; flex-shrink: 0; }\n    .ols-note-title h2, .ols-h5p-card h2, .ols-related-card h2 { margin: 0; font-size: clamp(28px, 3.5vw, 42px); line-height: 1.15; font-weight: 800; color: #111827; letter-spacing: -0.03em; }\n    .ols-h5p-card h2, .ols-related-card h2 { margin-bottom: 14px; }\n    .ols-note-card p, .ols-note-card li { font-size: clamp(15px, 1.25vw, 17px); line-height: 1.65; font-weight: 300; color: var(--body-text); }\n    .ols-h5p-card p, .ols-related-card p { font-size: clamp(15px, 1.3vw, 18px); line-height: 1.65; font-weight: 300; color: var(--body-text); }\n    .ols-note-card strong, .ols-h5p-card strong, .ols-related-card strong { font-weight: 700; color: var(--navy); }\n    .ols-note-card ul, .ols-note-card ol { margin: 0; padding-left: 22px; }\n    .ols-key-box { margin-top: 20px; background: var(--soft-green); border: 1px solid rgba(63, 143, 70, 0.25); border-radius: 20px; padding: 18px 20px; }\n    .ols-key-box p { margin: 0; font-weight: 400; color: var(--navy); }\n    .ols-rule-list { display: grid; gap: 14px; margin-top: 18px; }\n    .ols-rule-item { background: #ffffff; border: 1px solid var(--border); border-left: 5px solid var(--blue); border-radius: 18px; padding: 18px; box-shadow: var(--inner-shadow); }\n    .ols-rule-item h3 { margin: 0 0 8px; font-size: 20px; line-height: 1.25; color: var(--navy); }\n    .ols-rule-item p { margin: 0; font-size: 15px; line-height: 1.6; }\n    .ols-figure-card { margin: 26px 0 4px; border: 1px solid var(--border); border-radius: 26px; overflow: hidden; background: #ffffff; box-shadow: var(--inner-shadow); }\n    .ols-figure-image { width: 100%; min-height: 290px; display: flex; align-items: center; justify-content: center; background: #ffffff; padding: 24px; }\n    .ols-figure-image img { max-width: 100%; height: auto; display: block; }\n    .ols-figure-caption { padding: 18px 24px 22px; background: linear-gradient(135deg, #ffffff, #f8fbff); border-top: 1px solid var(--border); }\n    .ols-figure-caption p { margin: 0; color: #5f6b85; font-size: clamp(15px, 1.3vw, 17px); line-height: 1.6; font-weight: 300; font-style: italic; }\n    .ols-image-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; margin-top: 22px; }\n    .ols-mini-figure { background: #ffffff; border: 1px solid var(--border); border-radius: 22px; overflow: hidden; box-shadow: var(--inner-shadow); }\n    .ols-mini-figure-image { min-height: 230px; display: flex; align-items: center; justify-content: center; padding: 22px; background: #ffffff; }\n    .ols-mini-figure-image img { max-width: 100%; height: auto; display: block; }\n    .ols-mini-figure-caption { padding: 16px 18px 18px; border-top: 1px solid var(--border); background: linear-gradient(135deg, #ffffff, #f8fbff); }\n    .ols-mini-figure-caption p { margin: 0; font-size: 15px; line-height: 1.55; font-style: italic; color: #5f6b85; }\n    .ols-table-wrap { overflow: hidden; border-radius: 22px; border: 1px solid var(--border); background: #ffffff; margin-top: 18px; }\n    .ols-table { width: 100%; border-collapse: collapse; table-layout: fixed; }\n    .ols-table th { background: var(--navy); color: #ffffff; padding: 16px; text-align: left; font-size: clamp(14px, 1.2vw, 17px); font-weight: 600; overflow-wrap: anywhere; }\n    .ols-table td { padding: 16px; border-bottom: 1px solid var(--border); font-size: clamp(14px, 1.15vw, 16px); line-height: 1.45; color: var(--body-text); vertical-align: top; overflow-wrap: anywhere; }\n    .ols-table tr:last-child td { border-bottom: none; }\n    .ols-h5p-card { background: linear-gradient(135deg, #ffffff 0%, #f7f0ff 100%); }\n    .ols-h5p-frame { margin-top: 22px; padding: 18px; border-radius: 24px; background: #ffffff; border: 1px solid var(--border); box-shadow: inset 0 0 0 1px rgba(28, 36, 75, 0.03); }\n    .ols-related-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; margin-top: 18px; }\n    .ols-related-item { border: 1px solid var(--border); border-radius: 18px; padding: 18px; background: #ffffff; color: var(--navy); text-decoration: none; font-weight: 600; line-height: 1.5; transition: transform 0.2s ease, box-shadow 0.2s ease; }\n    .ols-related-item:hover { transform: translateY(-2px); box-shadow: 0 10px 22px rgba(28, 36, 75, 0.08); }\n\n    @media (max-width: 1050px) {\n      .ols-main { max-width: none; }\n      .ols-related-grid, .ols-image-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }\n    }\n\n    @media (max-width: 760px) {\n      .ols-title-card, .ols-note-card, .ols-h5p-card, .ols-related-card { padding: 24px 18px; border-radius: 22px; }\n      .ols-note-title { align-items: flex-start; }\n      .ols-figure-card, .ols-mini-figure { border-radius: 22px; }\n      .ols-figure-image { min-height: 220px; padding: 16px; }\n      .ols-mini-figure-image { min-height: 200px; padding: 16px; }\n      .ols-figure-caption, .ols-mini-figure-caption { padding: 16px; }\n      .ols-table-wrap { border: none; background: transparent; }\n      .ols-table, .ols-table thead, .ols-table tbody, .ols-table th, .ols-table td, .ols-table tr { display: block; width: 100%; }\n      .ols-table { border-collapse: separate; border-spacing: 0; }\n      .ols-table thead { display: none; }\n      .ols-table tr { margin-bottom: 14px; border: 1px solid var(--border); border-radius: 18px; overflow: hidden; background: #ffffff; box-shadow: var(--inner-shadow); }\n      .ols-table td { border-bottom: 1px solid var(--border); padding: 14px 16px; overflow-wrap: anywhere; }\n      .ols-table td:last-child { border-bottom: none; }\n      .ols-table td::before { content: attr(data-label); display: block; margin-bottom: 6px; font-size: 13px; font-weight: 700; color: var(--blue); }\n    }\n  \n.ols-faq-card,\n    .ols-quicksnap-card {\n      background: #ffffff;\n      border: 1px solid var(--border);\n      border-radius: 28px;\n      box-shadow: var(--shadow);\n      padding: 34px;\n      margin-bottom: 24px;\n      overflow: hidden;\n    }\n.ols-faq-card h2,\n    .ols-quicksnap-card h2,\n    .ols-infographic-title {\n      margin: 0;\n      font-size: clamp(28px, 3.5vw, 42px);\n      line-height: 1.15;\n      font-weight: 800;\n      color: #111827;\n      letter-spacing: -0.03em;\n    }\n.ols-faq-card h2,\n    .ols-quicksnap-card h2 {\n      margin-bottom: 14px;\n    }\n.ols-faq-card p,\n    .ols-quicksnap-card p {\n      font-size: clamp(15px, 1.25vw, 17px);\n      line-height: 1.65;\n      font-weight: 300;\n      color: var(--body-text);\n    }\n.ols-faq-card strong,\n    .ols-quicksnap-card strong {\n      font-weight: 700;\n      color: var(--navy);\n    }\n.ols-faq-list {\n      display: grid;\n      gap: 14px;\n      margin-top: 18px;\n    }\n.ols-faq-item {\n      background: #ffffff;\n      border: 1px solid var(--border);\n      border-radius: 18px;\n      padding: 18px 20px;\n      box-shadow: var(--inner-shadow);\n    }\n.ols-faq-item h3 {\n      margin: 0 0 8px;\n      font-size: 20px;\n      line-height: 1.3;\n      color: var(--navy);\n    }\n.ols-faq-item p {\n      margin: 0;\n      font-size: 16px;\n      line-height: 1.65;\n      color: var(--body-text);\n    }\n.ols-faq-card,\n      .ols-quicksnap-card,\n      .ols-attribution-card {\n        padding: 24px 18px;\n        border-radius: 22px;\n      }\n<\/style>\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<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\">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-6-organic-chemistry-i\/\">Topic 6 Organic Chemistry I<\/a> \/\n        <span>Carboxylic Acid<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Carboxylic Acid<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to the carboxylic acid functional group, the -oic acid suffix, numbering from the carboxylic acid carbon, dicarboxylic acids and examples such as ethanoic acid, propanoic acid and ethanedioic acid.<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Paper 2<\/div>\n          <div class=\"ols-badge\">Topic 6: Organic Chemistry I<\/div>\n          <div class=\"ols-badge\">9CH0\/02<\/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: Carboxylic Acids<\/h2>\n<p>Three quick questions on the carboxylic acids you met at GCSE.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"710\"><\/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 Is a Carboxylic Acid?<\/h2>\n        <\/div>\n\n        <p>A <strong>carboxylic acid<\/strong> is an organic compound containing the <strong>carboxyl functional group<\/strong>, written as <strong>-COOH<\/strong>.<\/p>\n        <p>The carboxyl group contains both a <strong>carbonyl bond<\/strong>, C=O, and a <strong>hydroxyl group<\/strong>, -OH, attached to the same carbon atom.<\/p>\n        <p>This functional group is found at the <strong>end of the carbon chain<\/strong>, so its carbon is included as part of the parent chain.<\/p>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Key idea:<\/strong> The carboxylic acid group is written as -COOH and the carbon in this group is counted as carbon 1 in the parent chain.<\/p>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n          <div class=\"ols-figure-image\">\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/skel-P066-carboxylic-acid-group.svg\" alt=\"The carboxylic acid functional group, \u2013COOH\" width=\"485\" height=\"414\">\n          <\/div>\n          <div class=\"ols-figure-caption\">\n            <p>The carboxyl group combines C=O and -OH on the same carbon atom, giving the characteristic -COOH group.<\/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: Find the Carboxylic Acids<\/h2>\n<p>Click every formula that contains a genuine -COOH group.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-89\" class=\"h5p-iframe\" data-content-id=\"89\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Carboxylic Acid Mark the Words: Find Every Carboxylic Acid\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">2<\/div>\n          <h2>Naming Carboxylic Acids Using the -oic Acid Suffix<\/h2>\n        <\/div>\n\n        <p>Carboxylic acids are named using the suffix <strong>-oic acid<\/strong>. This suffix replaces the final <strong>-e<\/strong> from the corresponding alkane name.<\/p>\n        <p>No position number is needed for the carboxylic acid group because it is <strong>always found at the end of the carbon chain<\/strong>.<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Homologous series<\/th>\n                <th>Functional group<\/th>\n                <th>Suffix<\/th>\n                <th>Example<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Homologous series\">Carboxylic acids<\/td>\n                <td data-label=\"Functional group\">-COOH<\/td>\n                <td data-label=\"Suffix\">-oic acid<\/td>\n                <td data-label=\"Example\">ethanoic acid<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-image-grid\">\n          <div class=\"ols-mini-figure\">\n            <div class=\"ols-mini-figure-image\">\n              <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/mol-ethanoic-acid.svg\" alt=\"Skeletal formula of ethanoic acid\" width=\"336\" height=\"302\">\n            <\/div>\n            <div class=\"ols-mini-figure-caption\">\n              <p>Ethanoic acid has a two-carbon chain and a terminal -COOH group.<\/p>\n            <\/div>\n          <\/div>\n\n          <div class=\"ols-mini-figure\">\n            <div class=\"ols-mini-figure-image\">\n              <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/mol-propanoic-acid.svg\" alt=\"Skeletal formula of propanoic acid\" width=\"414\" height=\"302\">\n            <\/div>\n            <div class=\"ols-mini-figure-caption\">\n              <p>Propanoic acid has a three-carbon chain, with the carboxyl carbon counted in the chain length.<\/p>\n            <\/div>\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: Name That Acid<\/h2>\n<p>Type the name of each new carboxylic acid.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-90\" class=\"h5p-iframe\" data-content-id=\"90\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Carboxylic Acid Flashcards: Name Four Unbranched Acids\"><\/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\">3<\/div>\n          <h2>Numbering Starts from the Carboxylic Acid Carbon<\/h2>\n        <\/div>\n\n        <p>When naming a carboxylic acid, numbering of the carbon chain <strong>always starts from the carboxylic acid carbon<\/strong>.<\/p>\n        <p>This means the carbon in the -COOH group is carbon 1. Any other functional groups or side chains are numbered relative to this carbon.<\/p>\n        <p>For example, <strong>3-hydroxy-4-methylpentanoic acid<\/strong> has the carboxylic acid carbon as carbon 1, the -OH group on carbon 3 and a methyl group on carbon 4.<\/p>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Exam focus:<\/strong> Do not number from the end closest to a side chain if the molecule contains -COOH. The carboxylic acid carbon controls the numbering direction.<\/p>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n          <div class=\"ols-figure-image\">\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/mol-3-hydroxy-4-methylpentanoic-acid.svg\" alt=\"Skeletal formula of 3-hydroxy-4-methylpentanoic acid\" width=\"546\" height=\"380\">\n          <\/div>\n          <div class=\"ols-figure-caption\">\n            <p>The substituent numbers are assigned after carbon 1 is fixed as the carboxylic acid carbon.<\/p>\n          <\/div>\n        <\/div>\n      <div class=\"ols-figure-card ols-zoom-pop\">\n<div class=\"ols-figure-image\">\n<a class=\"ols-image-fullscreen-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-02-priorityladder.jpg\" target=\"_blank\" rel=\"noopener\" aria-label=\"Open image fullscreen\">\n<img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-02-priorityladder.jpg\" alt=\"Ladder of naming priority from carboxylic acid down to halogen, with the suffix and prefix used for each group\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-02-priorityladder.jpg\">\n<\/a>\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: Numbering from the Carboxyl Carbon<\/h2>\n<p>Drag the words and numbers into place to name three substituted acids.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-88\" class=\"h5p-iframe\" data-content-id=\"88\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Carboxylic Acid Drag the Words: Numbering Three Substituted Acids\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">4<\/div>\n          <h2>Carboxylic Acid Groups at Both Ends<\/h2>\n        <\/div>\n\n        <p>If a molecule has carboxylic acid groups at <strong>both ends of the carbon chain<\/strong>, it is named as a <strong>dioic acid<\/strong>.<\/p>\n        <p>The suffix becomes <strong>-dioic acid<\/strong> to show that two -COOH groups are present.<\/p>\n\n        <div class=\"ols-rule-list\">\n          <div class=\"ols-rule-item\">\n            <h3>One -COOH group<\/h3>\n            <p>Use <strong>-oic acid<\/strong>, such as ethanoic acid or propanoic acid.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Two -COOH groups<\/h3>\n            <p>Use <strong>-dioic acid<\/strong>, such as ethanedioic acid.<\/p>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n          <div class=\"ols-figure-image\">\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/mol-ethanedioic-acid.svg\" alt=\"Skeletal formula of ethanedioic acid\" width=\"449\" height=\"392\">\n          <\/div>\n          <div class=\"ols-figure-caption\">\n            <p>The name ethanedioic acid shows a two-carbon parent chain with a carboxylic acid group at each end.<\/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: A Dioic Acid<\/h2>\n<p>Pick the structure that matches the name hexanedioic acid.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-91\" class=\"h5p-iframe\" data-content-id=\"91\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Carboxylic Acid MCQ: The Structure of Hexanedioic Acid\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">5<\/div>\n          <h2>Common Naming Points to Remember<\/h2>\n        <\/div>\n\n        <p>Carboxylic acid names are usually straightforward once the -COOH group has been identified. The most important step is to include the carboxyl carbon in the main chain and then number from that carbon.<\/p>\n        <p>The position of the carboxylic acid group is not written in the name because the -COOH group must be terminal. However, positions are still needed for other groups such as hydroxy or methyl groups.<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Naming point<\/th>\n                <th>Correct approach<\/th>\n                <th>Example<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Naming point\">Position of -COOH<\/td>\n                <td data-label=\"Correct approach\">Do not include a position number for the carboxylic acid group.<\/td>\n                <td data-label=\"Example\">propanoic acid<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Naming point\">Numbering direction<\/td>\n                <td data-label=\"Correct approach\">Start numbering from the carboxylic acid carbon.<\/td>\n                <td data-label=\"Example\">3-hydroxy-4-methylpentanoic acid<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Naming point\">Two -COOH groups<\/td>\n                <td data-label=\"Correct approach\">Use the suffix -dioic acid.<\/td>\n                <td data-label=\"Example\">ethanedioic acid<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Remember:<\/strong> The carboxylic acid carbon is part of the parent chain, not a side group.<\/p>\n        <\/div>\n      <div class=\"ols-figure-card ols-zoom-pop\">\n<div class=\"ols-figure-image\">\n<a class=\"ols-image-fullscreen-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-12-acidnaming.jpg\" target=\"_blank\" rel=\"noopener\" aria-label=\"Open image fullscreen\">\n<img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-12-acidnaming.jpg\" alt=\"The name 3-hydroxy-4-methylpentanoic acid taken apart, with a numbered five-carbon bead strip and a strip on -dioic acids\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-12-acidnaming.jpg\">\n<\/a>\n<\/div>\n<div class=\"ols-figure-caption\"><p>The COOH carbon is carbon 1 and counts in the stem, so substituents are numbered from it.<\/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: Spot the Naming Error<\/h2>\n<p>Choose the accurate statement in each round.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-711\" class=\"h5p-iframe\" data-content-id=\"711\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Carboxylic Acid Summary: Spot the Naming Error\"><\/iframe><\/div><\/div>\n<\/section>\n\n      \n<section class=\"ols-faq-card\">\n        <h2>FAQs<\/h2>\n        <p>These questions cover the carboxylic acid naming points that cost marks.<\/p>\n        <div class=\"ols-faq-list\">\n          <div class=\"ols-faq-item\">\n            <h3>Is the COOH carbon counted in the chain length?<\/h3>\n            <p>Yes. Ethanoic acid, CH\u2083COOH, has two carbons, and one of them is the COOH carbon.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Why is there no number for the acid group?<\/h3>\n            <p>The COOH group is always at the end of the chain, on carbon 1, so the number adds nothing.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Which end do I number from in a substituted acid?<\/h3>\n            <p>Always from the COOH carbon, which is carbon 1. A side chain nearer the other end does not change this.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>How is a molecule with COOH at both ends named?<\/h3>\n            <p>With the suffix -dioic acid and the e of the alkane kept: HOOCCOOH is ethanedioic acid.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Is the C=O in a carboxylic acid a ketone group?<\/h3>\n            <p>No. The C=O and the -OH on the same carbon form one carboxyl group, and it is named only as the acid.<\/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 Organic Chemistry Revision Notes<\/h2>\n        <p>Continue through Topic 6 by linking carboxylic acid naming to aldehydes, ketones and esters.<\/p>\n\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-6-organic-chemistry-i\/introduction-to-organic-chemistry\/aldehyde\/\">Aldehyde<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/ketone\/\">Ketone<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/ester\/\">Ester<\/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      \n      <\/main>\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-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/#webpage\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/\",\n            \"name\": \"Carboxylic Acid - Edexcel A Level Chemistry\",\n            \"headline\": \"Carboxylic Acid\",\n            \"description\": \"Revise carboxylic acids for Edexcel A Level Chemistry Topic 6 Organic Chemistry I, including the -COOH functional group, -oic acid suffix, numbering rules and dicarboxylic acid naming.\",\n            \"inLanguage\": \"en-GB\",\n            \"isPartOf\": {\n                \"@id\": \"https:\/\/www.onlinelearningsystem.net\/#website\"\n            },\n            \"publisher\": {\n                \"@id\": \"https:\/\/www.onlinelearningsystem.net\/#organization\"\n            },\n            \"author\": {\n                \"@type\": \"Person\",\n                \"name\": \"Dr. Mohammed Al-Fatah\"\n            },\n            \"breadcrumb\": {\n                \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/#breadcrumb\"\n            },\n            \"mainEntity\": {\n                \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/#course\"\n            }\n        },\n        {\n            \"@type\": \"WebSite\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/#website\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/\",\n            \"name\": \"Online Learning System\"\n        },\n        {\n            \"@type\": \"Organization\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/#organization\",\n            \"name\": \"Online Learning System\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/\"\n        },\n        {\n            \"@type\": \"BreadcrumbList\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/#breadcrumb\",\n            \"itemListElement\": [\n                {\n                    \"@type\": \"ListItem\",\n                    \"position\": 1,\n                    \"item\": {\n                        \"@type\": \"WebPage\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\",\n                        \"name\": \"Revision Notes\"\n                    }\n                },\n                {\n                    \"@type\": \"ListItem\",\n                    \"position\": 2,\n                    \"item\": {\n                        \"@type\": \"WebPage\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\",\n                        \"name\": \"A Level\"\n                    }\n                },\n                {\n                    \"@type\": \"ListItem\",\n                    \"position\": 3,\n                    \"item\": {\n                        \"@type\": \"WebPage\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\",\n                        \"name\": \"Chemistry\"\n                    }\n                },\n                {\n                    \"@type\": \"ListItem\",\n                    \"position\": 4,\n                    \"item\": {\n                        \"@type\": \"WebPage\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/\",\n                        \"name\": \"Edexcel\"\n                    }\n                },\n                {\n                    \"@type\": \"ListItem\",\n                    \"position\": 5,\n                    \"item\": {\n                        \"@type\": \"WebPage\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/\",\n                        \"name\": \"Topic 6 Organic Chemistry I\"\n                    }\n                },\n                {\n                    \"@type\": \"ListItem\",\n                    \"position\": 6,\n                    \"item\": {\n                        \"@type\": \"WebPage\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/\",\n                        \"name\": \"Carboxylic Acid\"\n                    }\n                }\n            ]\n        },\n        {\n            \"@type\": \"Course\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/#course\",\n            \"name\": \"Carboxylic Acid\",\n            \"description\": \"Revision notes for Edexcel A Level Chemistry Topic 6 Organic Chemistry I covering the carboxylic acid functional group, the -oic acid suffix, numbering from the carboxylic acid carbon and dicarboxylic acid naming.\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/\",\n            \"provider\": {\n                \"@type\": \"Organization\",\n                \"name\": \"Online Learning System\",\n                \"url\": \"https:\/\/www.onlinelearningsystem.net\/\"\n            },\n            \"educationalLevel\": \"A Level\",\n            \"inLanguage\": \"en-GB\",\n            \"about\": [\n                \"Carboxylic acids\",\n                \"Organic chemistry\",\n                \"IUPAC naming\",\n                \"Functional groups\",\n                \"Dicarboxylic acids\"\n            ],\n            \"teaches\": [\n                \"Recognise the carboxylic acid functional group\",\n                \"Use the -oic acid suffix to name carboxylic acids\",\n                \"Number carbon chains from the carboxylic acid carbon\",\n                \"Name dicarboxylic acids using the -dioic acid suffix\",\n                \"Avoid common carboxylic acid naming errors\"\n            ],\n            \"hasCourseInstance\": {\n                \"@type\": \"CourseInstance\",\n                \"courseMode\": \"Online\"\n            }\n        },\n        {\n            \"@type\": \"ImageObject\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/#carboxylic-acid-functional-group-image\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/skel-P066-carboxylic-acid-group.svg\",\n            \"contentUrl\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/skel-P066-carboxylic-acid-group.svg\",\n            \"name\": \"Carboxylic Acid Functional Group\",\n            \"caption\": \"Carboxylic acid functional group showing the -COOH group.\",\n            \"description\": \"Diagram showing the -COOH functional group of a carboxylic acid, containing C=O and -OH attached to the same carbon atom.\"\n        },\n        {\n            \"@type\": \"ItemList\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/#relatedtopics\",\n            \"name\": \"Related Organic Chemistry Revision Notes\",\n            \"itemListElement\": [\n                {\n                    \"@type\": \"ListItem\",\n                    \"position\": 1,\n                    \"item\": {\n                        \"@type\": \"Course\",\n                        \"name\": \"Aldehyde\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/aldehyde\/\",\n                        \"description\": \"Revision notes covering aldehyde functional groups and carbonyl naming.\"\n                    }\n                },\n                {\n                    \"@type\": \"ListItem\",\n                    \"position\": 2,\n                    \"item\": {\n                        \"@type\": \"Course\",\n                        \"name\": \"Ketone\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/ketone\/\",\n                        \"description\": \"Revision notes covering ketone functional groups and organic naming.\"\n                    }\n                },\n                {\n                    \"@type\": \"ListItem\",\n                    \"position\": 3,\n                    \"item\": {\n                        \"@type\": \"Course\",\n                        \"name\": \"Ester\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/ester\/\",\n                        \"description\": \"Revision notes covering ester functional groups and organic naming.\"\n                    }\n                }\n            ]\n        },\n        {\n            \"@type\": \"FAQPage\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/#faq\",\n            \"mainEntity\": [\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"Is the COOH carbon counted in the chain length?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"Yes. Ethanoic acid, CH\u2083COOH, has two carbons, and one of them is the COOH carbon.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"Why is there no number for the acid group?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"The COOH group is always at the end of the chain, on carbon 1, so the number adds nothing.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"Which end do I number from in a substituted acid?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"Always from the COOH carbon, which is carbon 1. A side chain nearer the other end does not change this.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"How is a molecule with COOH at both ends named?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"With the suffix -dioic acid and the e of the alkane kept: HOOCCOOH is ethanedioic acid.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"Is the C=O in a carboxylic acid a ketone group?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"No. The C=O and the -OH on the same carbon form one carboxyl group, and it is named only as the acid.\"\n                    }\n                }\n            ]\n        }\n    ]\n}\n<\/script>\n<\/section>\n","protected":false},"excerpt":{"rendered":"<p>Revision Notes \/ A Level \/ Chemistry \/ Edexcel \/ Topic 6 Organic Chemistry I \/ Carboxylic Acid Carboxylic Acid A concise revision guide to the carboxylic acid functional group, the -oic acid suffix, numbering from the carboxylic acid carbon, dicarboxylic acids and examples such as ethanoic acid, propanoic acid and ethanedioic acid. Paper 2 [&hellip;]<\/p>\n","protected":false},"author":12,"featured_media":0,"parent":4692,"menu_order":6,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-4819","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4819","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/comments?post=4819"}],"version-history":[{"count":0,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4819\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4692"}],"wp:attachment":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/media?parent=4819"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}