{"id":4963,"date":"2026-06-04T05:42:03","date_gmt":"2026-06-04T04:42:03","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/cp-8-analysis-of-inorganic-and-organic-unknowns\/"},"modified":"2026-06-09T10:17:54","modified_gmt":"2026-06-09T09:17:54","slug":"cp-8-analysis-of-inorganic-and-organic-unknowns","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-8-analysis-of-inorganic-and-organic-unknowns\/","title":{"rendered":"CP 8 Analysis of Inorganic and Organic Unknowns"},"content":{"rendered":"<p><!-- OLS Edexcel International IAL Unit 3 Core Practical page. Full HTML content to be added. --><\/p>\n\n\n<aside class=\"ols-sidebar\">\r\n  <div class=\"ols-sidebar-header\">\r\n    <h3>Revision Notes<\/h3>\r\n    <p>Edexcel International A Level Chemistry<\/p>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Core Practicals<\/h4>\r\n    <ul class=\"ols-topic-list\">\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-1-molar-volume-of-a-gas\/\">CP1: Molar Volume of a Gas<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-2-enthalpy-change-via-hess-law\/\">CP2: Hess's Law Enthalpy Change<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-3-concentration-of-hcl-by-titration\/\">CP3: Concentration of HCl<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-4-preparation-of-a-standard-solution\/\">CP4: Standard Solution Preparation<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-5-hydrolysis-of-halogenoalkanes\/\">CP5: Halogenoalkane Hydrolysis<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-6-chlorination-of-2-methylpropan-2-ol\/\">CP6: Chlorination of 2-methylpropan-2-ol<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-7-oxidation-of-propan-1-ol\/\">CP7: Oxidation of Propan-1-ol<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-8-analysis-of-inorganic-and-organic-unknowns\/\">CP8: Inorganic & Organic Unknowns<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-9a-9b-iodine-propanone-and-clock-reaction-kinetics\/\">CP9: Iodine-Propanone & Clock Reaction<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-10-activation-energy-of-a-reaction\/\">CP10: Activation Energy<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-11-ka-value-for-a-weak-acid\/\">CP11: Ka Value for Weak Acid<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-12-electrochemical-cells\/\">CP12: Electrochemical Cells<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-13a-13b-redox-titrations\/\">CP13: Redox Titrations<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-14-preparation-of-a-transition-metal-complex\/\">CP14: Transition Metal Complex Prep<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-15-analysis-of-inorganic-and-organic-unknowns\/\">CP15: Inorganic & Organic Unknowns<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-16-preparation-of-aspirin\/\">CP16: Preparation of Aspirin<\/a><\/li>\r\n    <\/ul>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Useful Links<\/h4>\r\n    <ul class=\"ols-topic-list\">\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/\">Edexcel International Chemistry<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-6-energetics\/\">Energetics<\/a><\/li>\r\n      <li><a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/\">Practical Skills<\/a><\/li>\r\n    <\/ul>\r\n  <\/div>\r\n<\/aside>\r\n\r\n<script>\r\ndocument.addEventListener('DOMContentLoaded', function () {\r\n  var currentPath = window.location.pathname.replace(\/\\\/$\/, '');\r\n  var sidebarLinks = document.querySelectorAll('.ols-sidebar .ols-topic-list a');\r\n\r\n  sidebarLinks.forEach(function (link) {\r\n    var linkPath = new URL(link.href, window.location.origin).pathname.replace(\/\\\/$\/, '');\r\n\r\n    if (linkPath === currentPath) {\r\n      link.closest('li').classList.add('active');\r\n    } else {\r\n      link.closest('li').classList.remove('active');\r\n    }\r\n  });\r\n});\r\n<\/script>\n\n<section class=\"ols-cp8-page\" id=\"ols-cp8-page\">\n  <style>\n    .ols-cp8-page {\n      --navy:#1C244B;\n      --blue:#2563eb;\n      --light-blue:#eef4ff;\n      --cream:#fff8ed;\n      --green:#eaf7ee;\n      --purple:#f6f0ff;\n      --red-soft:#fff2f2;\n      --gold:#c9973a;\n      --text:#1f2937;\n      --muted:#667085;\n      --border:rgba(28,36,75,.14);\n      --shadow:0 18px 45px rgba(28,36,75,.10);\n      --shadow-soft:0 10px 26px rgba(28,36,75,.08);\n      font-family:Poppins,Arial,sans-serif;\n      color:var(--navy);\n      background:#fff;\n    }\n    .ols-cp8-page * { box-sizing:border-box; }\n    .ols-cp8-layout { max-width:1180px; margin:0 auto; padding:26px 18px 64px; }\n    .ols-cp8-sidebar { position:sticky; top:20px; align-self:start; background:#fff; border:1px solid var(--border); border-radius:24px; box-shadow:var(--shadow); overflow:hidden; }\n    .ols-cp8-sidebar-head { padding:22px; border-bottom:1px solid var(--border); background:linear-gradient(135deg,#fff,var(--light-blue)); }\n    .ols-cp8-sidebar-head h3 { margin:0 0 6px; font-size:21px; font-weight:800; color:var(--navy); }\n    .ols-cp8-sidebar-head p { margin:0; font-size:14px; line-height:1.5; color:var(--muted); }\n    .ols-cp8-topic-group { padding:18px 22px; border-bottom:1px solid var(--border); }\n    .ols-cp8-topic-group:last-child { border-bottom:0; }\n    .ols-cp8-topic-group h4 { margin:0 0 14px; font-size:17px; font-weight:800; color:var(--navy); }\n    .ols-cp8-topic-list { list-style:none; margin:0; padding:0; display:grid; gap:8px; }\n    .ols-cp8-topic-list li { border-radius:14px; font-size:15px; line-height:1.35; color:#344054; }\n    .ols-cp8-topic-list li.active { padding:11px 12px; background:var(--light-blue); color:var(--blue); font-weight:800; }\n    .ols-cp8-topic-list a { display:block; padding:11px 12px; border-radius:14px; text-decoration:none; color:#344054; transition:background .2s ease,color .2s ease,transform .2s ease; }\n    .ols-cp8-topic-list a:hover { background:var(--light-blue); color:var(--blue); transform:translateX(2px); }\n\n    .ols-cp8-main { min-width:0; max-width:none; }\n    .ols-cp8-breadcrumbs { display:flex; flex-wrap:wrap; gap:8px; margin:10px 0 22px; font-size:15px; color:var(--muted); }\n    .ols-cp8-breadcrumbs a, .ols-cp8-breadcrumbs span { color:var(--muted); text-decoration:none; font-weight:650; }\n    .ols-cp8-breadcrumbs a:hover { color:var(--blue); text-decoration:underline; text-underline-offset:3px; }\n\n    .ols-title-card, .ols-note-card, .ols-related-card { background:#fff; border:1px solid var(--border); border-radius:28px; box-shadow:var(--shadow); padding:34px; margin-bottom:24px; overflow:visible; }\n    .ols-title-card { background:linear-gradient(135deg,#fff 0%,#f8fbff 100%); }\n    .ols-title-card h1 { margin:0 0 18px; font-size:clamp(36px,5vw,58px); line-height:1.08; font-weight:850; letter-spacing:-.04em; color:#111827; }\n    .ols-title-card p, .ols-note-card p, .ols-note-card li, .ols-related-card p { color:var(--text); font-size:clamp(15px,1.25vw,17px); line-height:1.7; font-weight:300; }\n    .ols-title-card .ols-page-intro { font-size:19px; 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:#fff; border:1px solid var(--border); font-size:15px; font-weight:700; color:var(--navy); }\n    .ols-author {\n      display:flex;\n      align-items:center;\n      gap:20px;\n      padding:28px;\n      margin-top:22px;\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    .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:0 14px 32px rgba(28,36,75,0.18),0 0 0 1px rgba(28,36,75,0.10);\n      transition:transform 0.25s ease,box-shadow 0.25s ease;\n    }\n    .ols-author:hover .ols-author-avatar-img {\n      transform:scale(1.04);\n      box-shadow:0 20px 42px rgba(28,36,75,0.22),0 0 0 1px rgba(28,36,75,0.10);\n    }\n    .ols-author-content { min-width:0; }\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:var(--navy);\n      letter-spacing:-0.03em;\n    }\n    .ols-author-description {\n      margin:0;\n      font-size:17px;\n      line-height:1.7;\n      font-weight:300;\n      color:var(--muted);\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;\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:transform 0.22s ease,box-shadow 0.22s ease;\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(120deg,rgba(255,255,255,0) 0%,rgba(255,255,255,0.28) 50%,rgba(255,255,255,0) 100%);\n      transition:left 0.7s ease;\n    }\n    .ols-linkedin-pill:hover {\n      transform:translateY(-3px) scale(1.03);\n      box-shadow:0 16px 34px rgba(10,102,194,0.34),0 0 0 6px rgba(10,102,194,0.10);\n      color:#ffffff;\n    }\n    .ols-linkedin-pill:hover::before { left:120%; }\n    .ols-linkedin-icon { width:18px; height:18px; display:block; flex-shrink:0; }\n\n    .ols-note-card.soft { background:linear-gradient(135deg,#fff 0%,var(--cream) 100%); }\n    .ols-note-card.blue { background:linear-gradient(135deg,#fff 0%,var(--light-blue) 100%); }\n    .ols-note-card.green { background:linear-gradient(135deg,#fff 0%,var(--green) 100%); }\n    .ols-note-card.purple { background:linear-gradient(135deg,#fff 0%,var(--purple) 100%); }\n    .ols-note-card.red { background:linear-gradient(135deg,#fff 0%,var(--red-soft) 100%); }\n\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:#fff; display:grid; place-items:center; font-size:24px; font-weight:850; flex-shrink:0; }\n    .ols-note-title h2, .ols-related-card h2, .ols-infographic-title { margin:0; font-size:clamp(28px,3.5vw,42px); line-height:1.15; font-weight:850; color:#111827; letter-spacing:-.03em; }\n    .ols-note-card h3 { margin:22px 0 10px; font-size:clamp(21px,2vw,28px); line-height:1.2; font-weight:800; color:var(--navy); }\n    .ols-note-card strong, .ols-related-card strong { font-weight:800; color:var(--navy); }\n    .ols-note-card ul, .ols-note-card ol { margin:10px 0 0; padding-left:22px; }\n\n    .ols-key-box { margin-top:20px; background:#fff; border:1px solid rgba(37,99,235,.18); border-left:6px solid var(--blue); border-radius:20px; padding:18px 20px; box-shadow:var(--shadow-soft); }\n    .ols-key-box p { margin:0; font-weight:400; color:var(--navy); }\n    .ols-warning-box { margin-top:20px; background:#fff7ed; border:1px solid rgba(201,151,58,.28); border-left:6px solid var(--gold); border-radius:20px; padding:18px 20px; }\n    .ols-warning-box p { margin:0; color:var(--navy); font-weight:400; }\n\n    .ols-table-wrap { overflow-x:auto; border:1px solid var(--border); border-radius:22px; background:#fff; margin:18px 0 4px; box-shadow:var(--shadow-soft); }\n    .ols-table { width:100%; min-width:720px; border-collapse:collapse; }\n    .ols-table th { background:var(--navy); color:#fff; padding:15px; text-align:left; font-size:15px; font-weight:750; vertical-align:top; }\n    .ols-table td { padding:15px; border-bottom:1px solid var(--border); font-size:15px; line-height:1.55; color:var(--text); vertical-align:top; }\n    .ols-table tr:last-child td { border-bottom:0; }\n    .ols-table .yes { color:#067647; font-weight:800; }\n    .ols-table .no { color:#667085; font-weight:700; }\n\n    .ols-image-grid { display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:18px; margin-top:22px; overflow:visible; }\n    .ols-image-card { background:#fff; border:1px solid var(--border); border-radius:24px; overflow:visible; box-shadow:var(--shadow-soft); }\n    .ols-image-frame { border-radius:24px 24px 0 0; overflow:visible; background:#fff; position:relative; cursor:zoom-in; display:block; }\n    .ols-image-frame::after { content:\"Click to enlarge\"; position:absolute; right:14px; bottom:14px; z-index:3; padding:8px 12px; border-radius:999px; background:rgba(28,36,75,.88); color:#fff; font-size:12px; line-height:1; font-weight:800; opacity:0; transform:translateY(6px); transition:opacity .22s ease, transform .22s ease; pointer-events:none; }\n    .ols-image-frame:hover::after { opacity:1; transform:translateY(0); }\n    .ols-image-card { position:relative; z-index:1; }\n    .ols-image-card img { width:100%; height:auto; display:block; cursor:zoom-in; transition:transform .32s ease, box-shadow .32s ease, filter .32s ease; transform-origin:center center; will-change:transform; position:relative; z-index:2; }\n    @media (hover:hover) and (pointer:fine) {\n      .ols-image-card .ols-image-frame:hover img { transform:scale(1.5); box-shadow:0 30px 80px rgba(28,36,75,.28); filter:saturate(1.05) contrast(1.03); }\n      .ols-image-card:hover { z-index:50; }\n    }\n    .ols-image-caption { padding:18px 20px 20px; background:linear-gradient(135deg,#fff,#f8fbff); border-radius:0 0 24px 24px; }\n    .ols-image-caption h3 { margin:0 0 8px; font-size:20px; line-height:1.25; color:var(--navy); }\n    .ols-image-caption p { margin:0; font-size:15px; line-height:1.6; color:#5f6b85; font-weight:300; }\n\n    .ols-full-image { width:100%; margin:10px 0 30px; overflow:visible; }\n    .ols-full-image .ols-image-card { border-radius:26px; }\n    .ols-full-image img { border-radius:26px 26px 0 0; }\n\n    .ols-evidence-strip { display:grid; grid-template-columns:repeat(5,minmax(0,1fr)); gap:12px; margin:22px 0 2px; }\n    .ols-evidence-step { background:#fff; border:1px solid var(--border); border-radius:18px; padding:16px; text-align:center; box-shadow:var(--shadow-soft); }\n    .ols-evidence-step span { display:block; font-size:26px; line-height:1; margin-bottom:8px; }\n    .ols-evidence-step strong { display:block; color:var(--navy); font-size:14px; line-height:1.35; }\n\n    .ols-chip-row { display:flex; flex-wrap:wrap; gap:10px; margin-top:16px; }\n    .ols-chip { padding:9px 12px; border-radius:999px; background:#fff; border:1px solid var(--border); color:var(--navy); font-size:14px; font-weight:750; }\n\n    .ols-interactive { background:linear-gradient(135deg,#fff,#f7f0ff); border:1px solid var(--border); border-radius:28px; box-shadow:var(--shadow); padding:30px; margin-bottom:24px; }\n    .ols-interactive h2 { margin:0 0 10px; font-size:clamp(28px,3.5vw,42px); line-height:1.15; font-weight:850; color:#111827; letter-spacing:-.03em; }\n    .ols-interactive p { margin:0 0 18px; color:var(--text); font-size:16px; line-height:1.7; font-weight:300; }\n    .ols-interactive-controls { display:flex; flex-wrap:wrap; gap:10px; margin:18px 0; }\n    .ols-interactive button { border:0; border-radius:999px; padding:12px 16px; background:var(--navy); color:#fff; font-family:Poppins,Arial,sans-serif; font-size:14px; font-weight:800; cursor:pointer; box-shadow:0 8px 20px rgba(28,36,75,.18); transition:transform .2s ease, background .2s ease; }\n    .ols-interactive button:hover { transform:translateY(-2px); background:#0f4fa8; }\n    .ols-interactive button.is-active { background:var(--blue); }\n    .ols-result-panel { display:none; background:#fff; border:1px solid var(--border); border-radius:22px; padding:18px; box-shadow:var(--shadow-soft); }\n    .ols-result-panel.is-visible { display:block; }\n    .ols-result-panel h3 { margin:0 0 8px; font-size:22px; color:var(--navy); }\n    .ols-result-panel p { margin:0 0 10px; }\n    .ols-result-panel ul { margin:0; padding-left:22px; }\n    .ols-result-panel li { color:var(--text); font-size:15px; line-height:1.7; }\n\n    .ols-equation-grid { display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:14px; margin-top:18px; }\n    .ols-equation-card { background:#fff; border:1px solid var(--border); border-radius:18px; padding:18px; box-shadow:var(--shadow-soft); }\n    .ols-equation-card h3 { margin:0 0 10px; font-size:18px; color:var(--navy); }\n    .ols-equation { font-family:Poppins,Arial,sans-serif; font-size:17px; line-height:1.6; color:#111827; font-weight:700; }\n\n    .ols-related-grid { display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:16px; margin-top:18px; }\n    .ols-related-item { display:block; border:1px solid var(--border); border-radius:18px; padding:18px; background:#fff; color:var(--navy); text-decoration:none; font-weight:750; line-height:1.5; transition:transform .2s ease, box-shadow .2s ease, background .2s ease; }\n    .ols-related-item:hover { transform:translateY(-2px); box-shadow:0 10px 22px rgba(28,36,75,.08); background:#f8fbff; }\n\n    .ols-lightbox { position:fixed; inset:0; background:rgba(8,13,31,.88); backdrop-filter:blur(6px); z-index:999999; display:none; align-items:center; justify-content:center; padding:24px; }\n    .ols-lightbox.is-open { display:flex; }\n    .ols-lightbox img { max-width:min(96vw,1500px); max-height:92vh; width:auto; height:auto; display:block; border-radius:18px; box-shadow:0 30px 90px rgba(0,0,0,.38); background:#fff; }\n    .ols-lightbox button { position:absolute; top:18px; right:18px; width:44px; height:44px; border-radius:999px; border:1px solid rgba(255,255,255,.35); background:#fff; color:var(--navy); font-family:Poppins,Arial,sans-serif; font-size:26px; line-height:1; cursor:pointer; font-weight:800; box-shadow:0 14px 36px rgba(0,0,0,.24); }\n    .ols-lightbox button:hover { background:var(--light-blue); }\n    .ols-lightbox p { position:absolute; left:28px; right:84px; bottom:16px; margin:0; color:#fff; font-size:14px; line-height:1.4; }\n\n    @media (max-width:1050px) {\n      .ols-cp8-main { max-width:none; }\n    }\n    @media (max-width:760px) {\n      .ols-cp8-layout { padding:18px 12px 48px; }\n      .ols-title-card, .ols-note-card, .ols-related-card, .ols-interactive { padding:24px 18px; border-radius:22px; }\n      .ols-note-title { align-items:flex-start; }\n      .ols-image-grid, .ols-equation-grid, .ols-related-grid, .ols-evidence-strip { grid-template-columns:1fr; }\n      .ols-cp8-topic-list { grid-template-columns:1fr; }\n      .ols-author { align-items:flex-start; padding:22px 18px; border-radius:22px; }\n      .ols-author-avatar-img { width:72px; height:72px; }\n      .ols-author-title { font-size:24px; }\n      .ols-author-description { font-size:15px; }\n      .ols-image-card, .ols-image-frame { border-radius:20px; }\n      .ols-image-frame { border-radius:20px 20px 0 0; }\n      .ols-lightbox { padding:12px; }\n      .ols-lightbox p { display:none; }\n    }\n  <\/style>\n\n  <div class=\"ols-cp8-layout\">\n\n    <main class=\"ols-cp8-main\">\n      <nav class=\"ols-cp8-breadcrumbs\" aria-label=\"Breadcrumb\">\n        <a href=\"\/xyz\/revision-notes\/\">Revision Notes<\/a> \/\n        <a href=\"\/xyz\/revision-notes\/a-level-chemistry\/\">A Level Chemistry<\/a> \/\n        <a href=\"\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/\">Edexcel International<\/a> \/\n        <a href=\"\/xyz\/edexcel-international\/core-practicals\/\">Core Practicals<\/a> \/\n        <span>Core Practical 8<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Core Practical 8: Analysis of Organic and Inorganic Unknowns<\/h1>\n        <p class=\"ols-page-intro\">This practical is an evidence trail. Students test unknown organic liquids A, B and C, then inorganic solids X, Y and Z. The exam skill is to connect each observation to an inference, then use the full pattern of results to identify the unknown.<\/p>\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Exam board: Edexcel International<\/div>\n          <div class=\"ols-badge\">Unit 3: Practical Skills in Chemistry I<\/div>\n          <div class=\"ols-badge\">Core Practical 8<\/div>\n        <\/div>\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          <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            <a class=\"ols-linkedin-pill\" href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n              <svg class=\"ols-linkedin-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\">\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      <\/header>\n\n      <section class=\"ols-full-image\" aria-label=\"CP8 complete summary infographic\">\n        <div class=\"ols-image-card\">\n          <div class=\"ols-image-frame\">\n            <img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Core-practical-analysis-of-unknowns.webp\" alt=\"Core practical 8 analysis of organic and inorganic unknowns summary infographic\">\n          <\/div>\n          <div class=\"ols-image-caption\">\n            <h3>The CP8 evidence trail<\/h3>\n            <p>Unknown \u2192 test \u2192 observation \u2192 inference \u2192 identity. This is the logic students should use throughout the practical.<\/p>\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">1<\/div>\n          <h2>How CP8 Works<\/h2>\n        <\/div>\n        <p>The objective is to identify several unknown colourless organic liquids and inorganic solids. The practical does not rely on one isolated result. It relies on the <strong>pattern<\/strong> of positive and negative tests.<\/p>\n        <div class=\"ols-evidence-strip\">\n          <div class=\"ols-evidence-step\"><span>?<\/span><strong>Unknown<\/strong><\/div>\n          <div class=\"ols-evidence-step\"><span>\ud83e\uddea<\/span><strong>Test<\/strong><\/div>\n          <div class=\"ols-evidence-step\"><span>\ud83d\udc41<\/span><strong>Observation<\/strong><\/div>\n          <div class=\"ols-evidence-step\"><span>\u2192<\/span><strong>Inference<\/strong><\/div>\n          <div class=\"ols-evidence-step\"><span>\u2713<\/span><strong>Identity<\/strong><\/div>\n        <\/div>\n        <div class=\"ols-key-box\">\n          <p><strong>Key idea:<\/strong> Negative tests are useful. They tell you what the unknown is not, which helps remove incorrect identities.<\/p>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card blue\" id=\"organic-unknowns\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">2<\/div>\n          <h2>Organic Unknowns A, B and C<\/h2>\n        <\/div>\n        <p>The organic section uses four tests: bromine water, acidified potassium dichromate(VI), Fehling\u2019s solution, and hydrolysis followed by silver nitrate. In the sample data, each organic unknown is identified by the test it responds to.<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Test<\/th>\n                <th>A<\/th>\n                <th>B<\/th>\n                <th>C<\/th>\n                <th>Inference<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td><strong>Bromine water<\/strong><\/td>\n                <td class=\"no\">No change<\/td>\n                <td class=\"yes\">Orange \u2192 colourless<\/td>\n                <td class=\"no\">No change<\/td>\n                <td>B contains a C=C double bond, so B is an alkene.<\/td>\n              <\/tr>\n              <tr>\n                <td><strong>Acidified potassium dichromate(VI)<\/strong><\/td>\n                <td class=\"yes\">Orange \u2192 green<\/td>\n                <td class=\"no\">No change<\/td>\n                <td class=\"no\">No change<\/td>\n                <td>A is oxidised, so A contains an oxidisable functional group.<\/td>\n              <\/tr>\n              <tr>\n                <td><strong>Fehling\u2019s solution<\/strong><\/td>\n                <td class=\"no\">No brick-red precipitate<\/td>\n                <td class=\"no\">No brick-red precipitate<\/td>\n                <td class=\"no\">No brick-red precipitate<\/td>\n                <td>No aldehyde is detected in the sample data.<\/td>\n              <\/tr>\n              <tr>\n                <td><strong>Hydrolysis, acidification, then AgNO<sub>3<\/sub><\/strong><\/td>\n                <td class=\"no\">No precipitate<\/td>\n                <td class=\"no\">No precipitate<\/td>\n                <td class=\"yes\">Cream precipitate<\/td>\n                <td>C contains bromine after hydrolysis, so C is a bromoalkane.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Final organic identifications:<\/strong> A = oxidisable alcohol, B = alkene, C = bromoalkane.<\/p>\n        <\/div>\n\n        <div class=\"ols-image-grid\">\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Bromine-water-test-in-laboratory-setting.webp\" alt=\"Bromine water test showing only B decolourising from orange to colourless\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Bromine water<\/h3><p>Only B decolourises bromine water. This is evidence for an alkene.<\/p><\/div>\n          <\/div>\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Acidified-dichromate-test-setup.webp\" alt=\"Acidified potassium dichromate test showing orange to green colour change for A\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Acidified dichromate<\/h3><p>Only A changes from orange to green, showing oxidation.<\/p><\/div>\n          <\/div>\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Fehlings-Solution-Test-in-action.webp\" alt=\"Fehling solution test showing no brick-red precipitate in the CP8 sample data\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Fehling\u2019s solution<\/h3><p>No brick-red precipitate forms in the CP8 sample data, so an aldehyde is not detected.<\/p><\/div>\n          <\/div>\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Silver-nitrate-test-after-hydrolysis.webp\" alt=\"Silver nitrate test after hydrolysis showing cream precipitate for bromoalkane C\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Hydrolysis then silver nitrate<\/h3><p>C gives a cream precipitate after hydrolysis, acidification and silver nitrate, consistent with a bromoalkane.<\/p><\/div>\n          <\/div>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card red\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">3<\/div>\n          <h2>Fehling\u2019s Test: Positive Control<\/h2>\n        <\/div>\n        <p>The CP8 sample data gives no Fehling\u2019s reaction. However, students still need to recognise what a positive result would look like. Aldehydes reduce Fehling\u2019s solution to a <strong>brick-red precipitate<\/strong> of copper(I) oxide. Ketones do not react under these conditions.<\/p>\n        <div class=\"ols-image-grid\">\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Positive-Fehlings-test-in-lab-setting.webp\" alt=\"Positive Fehling test showing brick red precipitate as a reference result for aldehydes\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Reference positive result<\/h3><p>This is a positive control image, not the CP8 sample result. A brick-red precipitate would indicate an aldehyde.<\/p><\/div>\n          <\/div>\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Halide-ion-test-in-lab-setting.webp\" alt=\"Halide ion test comparison showing white, cream and pale yellow silver halide precipitates\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Link to silver halides<\/h3><p>After hydrolysis, silver nitrate can detect released halide ions by precipitate colour.<\/p><\/div>\n          <\/div>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card green\" id=\"inorganic-unknowns\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">4<\/div>\n          <h2>Inorganic Unknowns X, Y and Z<\/h2>\n        <\/div>\n        <p>The inorganic section uses flame tests to identify cations, then precipitation and displacement tests to identify anions. The full identity comes from combining cation and anion evidence.<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Test<\/th>\n                <th>X<\/th>\n                <th>Y<\/th>\n                <th>Z<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td><strong>Flame test<\/strong><\/td>\n                <td>Red-orange, so Ca<sup>2+<\/sup><\/td>\n                <td>Yellow, so Na<sup>+<\/sup><\/td>\n                <td>Lilac, so K<sup>+<\/sup><\/td>\n              <\/tr>\n              <tr>\n                <td><strong>HNO<sub>3<\/sub>, AgNO<sub>3<\/sub>, then dilute NH<sub>3<\/sub><\/strong><\/td>\n                <td>Cream precipitate, not dissolved in dilute NH<sub>3<\/sub>, so Br<sup>&#8211;<\/sup><\/td>\n                <td>No change<\/td>\n                <td>Fizzing with acid, then no further silver halide evidence<\/td>\n              <\/tr>\n              <tr>\n                <td><strong>HNO<sub>3<\/sub>, then BaCl<sub>2<\/sub><\/strong><\/td>\n                <td>No change<\/td>\n                <td>White precipitate, so SO<sub>4<\/sub><sup>2-<\/sup><\/td>\n                <td>Fizzing with acid, then no lasting white precipitate<\/td>\n              <\/tr>\n              <tr>\n                <td><strong>Chlorine water<\/strong><\/td>\n                <td>Orange solution forms, so Br<sub>2<\/sub> is produced from Br<sup>&#8211;<\/sup><\/td>\n                <td>No change<\/td>\n                <td>Slight fizzing<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Final inorganic identifications:<\/strong> X = calcium bromide, CaBr<sub>2<\/sub>; Y = sodium sulfate, Na<sub>2<\/sub>SO<sub>4<\/sub>; Z = potassium carbonate, K<sub>2<\/sub>CO<sub>3<\/sub>.<\/p>\n        <\/div>\n\n        <div class=\"ols-image-grid\">\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Flame-test-colours-and-cation-identification.webp\" alt=\"Flame test colours for required metal cations including lithium sodium potassium calcium strontium and barium\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Flame tests<\/h3><p>Students should recognise the required cation colours, including Na<sup>+<\/sup> yellow, K<sup>+<\/sup> lilac and Ca<sup>2+<\/sup> brick red or red-orange.<\/p><\/div>\n          <\/div>\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Halide-ion-test-in-lab-setting.webp\" alt=\"Silver nitrate halide test showing chloride bromide and iodide precipitates\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Halide ion test<\/h3><p>Silver nitrate gives AgCl white, AgBr cream and AgI pale yellow. X gives the bromide result.<\/p><\/div>\n          <\/div>\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Sulfate-ion-test-infographic-and-lab-setup.webp\" alt=\"Sulfate ion test showing white barium sulfate precipitate\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Sulfate ion test<\/h3><p>Y gives a white precipitate with acidified barium chloride, showing sulfate ions.<\/p><\/div>\n          <\/div>\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Carbonate-ion-test-demonstration.webp\" alt=\"Carbonate ion test showing fizzing with acid and cloudy limewater\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Carbonate clue<\/h3><p>Z fizzes with acid, showing carbonate ions are present.<\/p><\/div>\n          <\/div>\n        <\/div>\n      <\/article>\n\n      <section class=\"ols-full-image\" aria-label=\"CP8 inorganic evidence guide\">\n        <div class=\"ols-image-card\">\n          <div class=\"ols-image-frame\">\n            <img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/CP8-Inorganic-Unknowns-Identification-Guide.webp\" alt=\"CP8 inorganic unknowns identification guide for calcium bromide sodium sulfate and potassium carbonate\">\n          <\/div>\n          <div class=\"ols-image-caption\">\n            <h3>Inorganic unknowns guide<\/h3>\n            <p>This visual summary links the flame test, halide test, sulfate test and chlorine water test to X, Y and Z.<\/p>\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">5<\/div>\n          <h2>Chlorine Water Displacement<\/h2>\n        <\/div>\n        <p>Chlorine is more reactive than bromine and iodine, so chlorine can displace bromide and iodide ions from solution. In CP8, X forms an orange solution with chlorine water, showing that bromide ions have been oxidised to bromine.<\/p>\n        <div class=\"ols-image-grid\">\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Chlorine-water-displacement-reactions.webp\" alt=\"Chlorine water displacement reactions showing chloride bromide and iodide results\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Displacement comparison<\/h3><p>Chloride gives no visible displacement, bromide gives orange bromine, and iodide gives brown iodine.<\/p><\/div>\n          <\/div>\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-frame\"><img decoding=\"async\" class=\"ols-lightbox-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/06\/Silver-nitrate-test-after-hydrolysis.webp\" alt=\"Cream silver bromide precipitate after hydrolysis and silver nitrate addition\"><\/div>\n            <div class=\"ols-image-caption\"><h3>Consistent evidence for bromide<\/h3><p>The chlorine water result agrees with the cream AgBr precipitate from the silver nitrate test.<\/p><\/div>\n          <\/div>\n        <\/div>\n      <\/article>\n\n      <section class=\"ols-interactive\" id=\"interactive-evidence\">\n        <h2>Interactive Evidence Trail<\/h2>\n        <p>Click each button to reveal how the observations lead to the identity. This mirrors the thinking students need in the practical and in exam questions.<\/p>\n        <div class=\"ols-interactive-controls\">\n          <button type=\"button\" data-target=\"ols-a\">Identify A<\/button>\n          <button type=\"button\" data-target=\"ols-b\">Identify B<\/button>\n          <button type=\"button\" data-target=\"ols-c\">Identify C<\/button>\n          <button type=\"button\" data-target=\"ols-x\">Identify X<\/button>\n          <button type=\"button\" data-target=\"ols-y\">Identify Y<\/button>\n          <button type=\"button\" data-target=\"ols-z\">Identify Z<\/button>\n        <\/div>\n\n        <div id=\"ols-a\" class=\"ols-result-panel is-visible\">\n          <h3>A = oxidisable alcohol<\/h3>\n          <ul>\n            <li>Acidified dichromate changes orange to green.<\/li>\n            <li>Fehling\u2019s solution gives no brick-red precipitate.<\/li>\n            <li>The best functional-group inference is an oxidisable alcohol rather than an aldehyde.<\/li>\n          <\/ul>\n        <\/div>\n\n        <div id=\"ols-b\" class=\"ols-result-panel\">\n          <h3>B = alkene<\/h3>\n          <ul>\n            <li>Bromine water changes from orange to colourless.<\/li>\n            <li>This is an addition reaction across a C=C double bond.<\/li>\n            <li>The organic product is a 1,2-dibromo compound.<\/li>\n          <\/ul>\n        <\/div>\n\n        <div id=\"ols-c\" class=\"ols-result-panel\">\n          <h3>C = bromoalkane<\/h3>\n          <ul>\n            <li>C is warmed with ethanol and sodium hydroxide to hydrolyse the halogenoalkane.<\/li>\n            <li>The mixture is acidified with nitric acid before silver nitrate is added.<\/li>\n            <li>A cream precipitate shows AgBr, so C is a bromoalkane.<\/li>\n          <\/ul>\n        <\/div>\n\n        <div id=\"ols-x\" class=\"ols-result-panel\">\n          <h3>X = calcium bromide, CaBr<sub>2<\/sub><\/h3>\n          <ul>\n            <li>Red-orange flame indicates Ca<sup>2+<\/sup>.<\/li>\n            <li>Cream precipitate with AgNO<sub>3<\/sub> indicates Br<sup>&#8211;<\/sup>.<\/li>\n            <li>Orange solution with chlorine water confirms Br<sub>2<\/sub> is formed from Br<sup>&#8211;<\/sup>.<\/li>\n          <\/ul>\n        <\/div>\n\n        <div id=\"ols-y\" class=\"ols-result-panel\">\n          <h3>Y = sodium sulfate, Na<sub>2<\/sub>SO<sub>4<\/sub><\/h3>\n          <ul>\n            <li>Yellow flame indicates Na<sup>+<\/sup>.<\/li>\n            <li>White precipitate with acidified barium chloride indicates SO<sub>4<\/sub><sup>2-<\/sup>.<\/li>\n            <li>No halide or chlorine-water displacement evidence is observed.<\/li>\n          <\/ul>\n        <\/div>\n\n        <div id=\"ols-z\" class=\"ols-result-panel\">\n          <h3>Z = potassium carbonate, K<sub>2<\/sub>CO<sub>3<\/sub><\/h3>\n          <ul>\n            <li>Lilac flame indicates K<sup>+<\/sup>.<\/li>\n            <li>Fizzing with acid indicates CO<sub>3<\/sub><sup>2-<\/sup>.<\/li>\n            <li>The carbonate ion reacts with acid to produce carbon dioxide gas.<\/li>\n          <\/ul>\n        <\/div>\n      <\/section>\n\n      <article class=\"ols-note-card blue\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">6<\/div>\n          <h2>Ionic Equations and Reagent Roles<\/h2>\n        <\/div>\n        <p>These are the equations students should be able to write from the CP8 data. They also explain why acidification is important before precipitation tests.<\/p>\n\n        <div class=\"ols-equation-grid\">\n          <div class=\"ols-equation-card\">\n            <h3>Carbonate with acid<\/h3>\n            <div class=\"ols-equation\">CO<sub>3<\/sub><sup>2-<\/sup> + 2H<sup>+<\/sup> \u2192 CO<sub>2<\/sub> + H<sub>2<\/sub>O<\/div>\n          <\/div>\n          <div class=\"ols-equation-card\">\n            <h3>Silver bromide precipitate<\/h3>\n            <div class=\"ols-equation\">Ag<sup>+<\/sup> + Br<sup>&#8211;<\/sup> \u2192 AgBr<\/div>\n          <\/div>\n          <div class=\"ols-equation-card\">\n            <h3>Barium sulfate precipitate<\/h3>\n            <div class=\"ols-equation\">Ba<sup>2+<\/sup> + SO<sub>4<\/sub><sup>2-<\/sup> \u2192 BaSO<sub>4<\/sub><\/div>\n          <\/div>\n          <div class=\"ols-equation-card\">\n            <h3>Bromide displaced by chlorine<\/h3>\n            <div class=\"ols-equation\">2Br<sup>&#8211;<\/sup> + Cl<sub>2<\/sub> \u2192 Br<sub>2<\/sub> + 2Cl<sup>&#8211;<\/sup><\/div>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-warning-box\">\n          <p><strong>Exam trap:<\/strong> Nitric acid is added before silver nitrate to react with carbonate ions. This prevents silver carbonate forming and masking the halide result.<\/p>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card soft\" id=\"exam-style\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">7<\/div>\n          <h2>Exam-Style Data Practice<\/h2>\n        <\/div>\n        <p>CP8 links directly to exam questions where students must identify unknowns from observations, spectra or calculation data.<\/p>\n\n        <h3>Unknown solution matrix<\/h3>\n        <p>Four unknown solutions are sodium carbonate, barium chloride, dilute hydrochloric acid and dilute sulfuric acid. From the pairwise observations, the identities are:<\/p>\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr><th>Letter<\/th><th>Identity<\/th><th>Reasoning clue<\/th><\/tr>\n            <\/thead>\n            <tbody>\n              <tr><td>A<\/td><td>Sulfuric acid<\/td><td>Forms a white precipitate with barium chloride and reacts with carbonate.<\/td><\/tr>\n              <tr><td>B<\/td><td>Hydrochloric acid<\/td><td>Reacts with carbonate but does not form a sulfate precipitate.<\/td><\/tr>\n              <tr><td>C<\/td><td>Barium chloride<\/td><td>Forms a white precipitate with sulfuric acid.<\/td><\/tr>\n              <tr><td>D<\/td><td>Sodium carbonate<\/td><td>Effervescence occurs with acids.<\/td><\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <h3>Spectroscopy and formula question<\/h3>\n        <p>The organic compound has percentage composition 38.7% carbon, 9.7% hydrogen and 52.6% oxygen. The answer pathway is:<\/p>\n        <ol>\n          <li>Empirical formula = CH<sub>2<\/sub>O.<\/li>\n          <li>Molecular ion peak at m\/z = 62, so M<sub>r<\/sub> = 62.<\/li>\n          <li>Molecular formula = C<sub>2<\/sub>H<sub>6<\/sub>O<sub>2<\/sub>.<\/li>\n          <li>Broad absorption at approximately 3400 cm<sup>-1<\/sup> shows O-H.<\/li>\n          <li>A fragment such as CHO<sup>+<\/sup> at m\/z 31 supports the structure.<\/li>\n          <li>The compound is CH<sub>2<\/sub>OHCH<sub>2<\/sub>OH, ethane-1,2-diol.<\/li>\n        <\/ol>\n      <\/article>\n\n      <article class=\"ols-note-card green\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">8<\/div>\n          <h2>What Students Usually Miss<\/h2>\n        <\/div>\n        <ul>\n          <li><strong>Do not ignore negative results.<\/strong> Fehling\u2019s solution has no reaction in the CP8 sample data, which helps rule out an aldehyde.<\/li>\n          <li><strong>Do not identify C directly from silver nitrate.<\/strong> The halogenoalkane must first be hydrolysed so halide ions are released.<\/li>\n          <li><strong>Do not forget acidification.<\/strong> Nitric acid removes carbonate interference before the silver nitrate test.<\/li>\n          <li><strong>Do not use flame colour alone for the full identity.<\/strong> The flame test gives the cation only. You still need the anion tests.<\/li>\n          <li><strong>Do not confuse AgBr and BaSO<sub>4<\/sub>.<\/strong> AgBr is cream and comes from silver nitrate with bromide. BaSO<sub>4<\/sub> is white and comes from barium chloride with sulfate.<\/li>\n        <\/ul>\n      <\/article>\n    <\/main>\n  <\/div>\n\n  <div class=\"ols-lightbox\" id=\"olsCp8Lightbox\" aria-hidden=\"true\">\n    <button type=\"button\" aria-label=\"Close image\">&times;<\/button>\n    <img decoding=\"async\" src=\"\" alt=\"\">\n    <p><\/p>\n  <\/div>\n\n  <script>\n    (function(){\n      var page = document.getElementById('ols-cp8-page');\n      if(!page) return;\n\n      var lb = page.querySelector('#olsCp8Lightbox');\n      var lbImg = lb.querySelector('img');\n      var lbText = lb.querySelector('p');\n      var closeBtn = lb.querySelector('button');\n\n      function openLightbox(img){\n        if(!img) return;\n        lbImg.src = img.currentSrc || img.src;\n        lbImg.alt = img.alt || '';\n        lbText.textContent = img.alt || 'Image preview';\n        lb.classList.add('is-open');\n        lb.setAttribute('aria-hidden','false');\n        document.documentElement.style.overflow = 'hidden';\n      }\n\n      function closeLightbox(){\n        lb.classList.remove('is-open');\n        lb.setAttribute('aria-hidden','true');\n        lbImg.src = '';\n        lbImg.alt = '';\n        lbText.textContent = '';\n        document.documentElement.style.overflow = '';\n      }\n\n      page.addEventListener('click', function(e){\n        var frame = e.target.closest('.ols-image-frame');\n        if(!frame || !page.contains(frame)) return;\n        var img = frame.querySelector('img');\n        openLightbox(img);\n      });\n\n      closeBtn.addEventListener('click', closeLightbox);\n      lb.addEventListener('click', function(e){\n        if(e.target === lb) closeLightbox();\n      });\n      document.addEventListener('keydown', function(e){\n        if(e.key === 'Escape') closeLightbox();\n      });\n\n      var interactive = page.querySelector('.ols-interactive');\n      if(interactive){\n        var buttons = interactive.querySelectorAll('button[data-target]');\n        var panels = interactive.querySelectorAll('.ols-result-panel');\n        buttons.forEach(function(btn){\n          btn.addEventListener('click', function(){\n            buttons.forEach(function(b){ b.classList.remove('is-active'); });\n            panels.forEach(function(p){ p.classList.remove('is-visible'); });\n            btn.classList.add('is-active');\n            var target = interactive.querySelector('#' + btn.getAttribute('data-target'));\n            if(target) target.classList.add('is-visible');\n          });\n        });\n      }\n    })();\n  <\/script>\n\n  <script type=\"application\/ld+json\">\n  {\n    \"@context\":\"https:\/\/schema.org\",\n    \"@type\":\"LearningResource\",\n    \"name\":\"Core Practical 8: Analysis of Organic and Inorganic Unknowns\",\n    \"description\":\"A Level Chemistry revision notes for Edexcel International Core Practical 8, covering organic and inorganic unknown analysis, flame tests, bromine water, acidified dichromate, Fehling's solution, silver nitrate, barium chloride and chlorine water displacement.\",\n    \"learningResourceType\":\"Revision notes\",\n    \"educationalLevel\":\"A Level\",\n    \"inLanguage\":\"en-GB\",\n    \"provider\":{\n      \"@type\":\"Organization\",\n      \"name\":\"Online Learning System\",\n      \"url\":\"https:\/\/www.onlinelearningsystem.net\/\"\n    },\n    \"about\":[\n      \"Core Practical 8\",\n      \"Qualitative analysis\",\n      \"Organic unknowns\",\n      \"Inorganic unknowns\",\n      \"Flame tests\",\n      \"Halide test\",\n      \"Sulfate test\",\n      \"Carbonate test\",\n      \"Bromine water\",\n      \"Acidified dichromate\"\n    ]\n  }\n  <\/script>\n<\/section>\n\n","protected":false},"excerpt":{"rendered":"<p>Revision Notes \/ A Level Chemistry \/ Edexcel International \/ Core Practicals \/ Core Practical 8 Core Practical 8: Analysis of Organic and Inorganic Unknowns This practical is an evidence trail. Students test unknown organic liquids A, B and C, then inorganic solids X, Y and Z. The exam skill is to connect each observation [&hellip;]<\/p>\n","protected":false},"author":12,"featured_media":0,"parent":5028,"menu_order":7,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-4963","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4963","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=4963"}],"version-history":[{"count":0,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4963\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/5028"}],"wp:attachment":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/media?parent=4963"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}