{"id":10970,"date":"2026-09-26T22:00:26","date_gmt":"2026-09-26T21:00:26","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/"},"modified":"2026-09-27T10:01:40","modified_gmt":"2026-09-27T09:01:40","slug":"cfcs-and-the-ozone-layer","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/","title":{"rendered":"CFCs and the Ozone Layer"},"content":{"rendered":"\n<section class=\"ols-revision-page ols-nature-of-covalent-bonding-9ch0-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, .ols-faq-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-direction: column; align-items: flex-start; 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 { display: flex; align-items: center; gap: 20px; padding: 28px; border-radius: 28px; background: linear-gradient(135deg, #ffffff 0%, #f8fbff 100%); border: 1px solid rgba(28,36,75,0.12); box-shadow: 0 18px 45px rgba(28,36,75,0.10); margin-top: 22px; }\n    .ols-author-avatar-img { width: 92px; height: 92px; border-radius: 50%; object-fit: cover; object-position: center; flex-shrink: 0; border: 4px solid #ffffff; box-shadow: 0 14px 32px rgba(28,36,75,0.18), 0 0 0 1px rgba(28,36,75,0.10); transition: transform 0.25s ease, box-shadow 0.25s ease; }\n    .ols-author:hover .ols-author-avatar-img { transform: scale(1.04); box-shadow: 0 20px 42px rgba(28,36,75,0.22), 0 0 0 1px rgba(28,36,75,0.10); }\n    .ols-author-content { min-width: 0; }\n    .ols-author-title { margin: 0 0 4px; font-size: clamp(24px,3vw,34px); line-height: 1.15; font-weight: 700; color: var(--navy); letter-spacing: -0.03em; }\n    .ols-author-description { margin: 0; font-size: 17px; line-height: 1.7; font-weight: 300; color: var(--grey-text); }\n    .ols-linkedin-pill { display: inline-flex; align-items: center; justify-content: center; gap: 10px; margin-top: 16px; padding: 11px 18px; border-radius: 999px; background: linear-gradient(135deg,#0A66C2,#004182); color: #ffffff; text-decoration: none; font-size: 14px; line-height: 1; font-weight: 700; letter-spacing: 0.01em; box-shadow: 0 10px 22px rgba(10,102,194,0.24); position: relative; overflow: hidden; transition: transform 0.22s ease, box-shadow 0.22s ease; }\n    .ols-linkedin-pill::before { content: \"\"; position: absolute; top: 0; left: -120%; width: 100%; height: 100%; background: linear-gradient(120deg, rgba(255,255,255,0) 0%, rgba(255,255,255,0.28) 50%, rgba(255,255,255,0) 100%); transition: left 0.7s ease; }\n    .ols-linkedin-pill:hover { transform: translateY(-3px) scale(1.03); box-shadow: 0 16px 34px rgba(10,102,194,0.34), 0 0 0 6px rgba(10,102,194,0.10); color: #ffffff; }\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, #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, .ols-faq-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, .ols-faq-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, .ols-faq-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, .ols-faq-card strong { font-weight: 700; color: var(--navy); }\n    .ols-note-card ul, .ols-note-card ol { margin: 0; padding-left: 22px; }\n\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-definition-box { background: linear-gradient(135deg, #ffffff, var(--soft-purple)); border: 2px dashed rgba(122, 62, 157, 0.35); border-radius: 24px; padding: 22px 24px; margin-top: 22px; }\n    .ols-definition-box p { margin: 0; color: var(--navy); font-weight: 400; }\n\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\n    .ols-figure-card { margin: 26px auto 4px; border: 1px solid var(--border); border-radius: 26px; overflow: hidden; background: #ffffff; box-shadow: var(--inner-shadow); max-width: 100%; }\n    .ols-figure-card.medium { max-width: 820px; }\n    .ols-figure-card.compact { max-width: 700px; }\n    .ols-figure-image { width: 100%; min-height: 260px; display: flex; align-items: center; justify-content: center; background: #ffffff; padding: 20px; }\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-zoom-card, .ols-zoom-card * { box-sizing: border-box; }\n    .ols-zoom-card { display: block !important; margin: 26px auto 34px !important; border: 1px solid rgba(28, 36, 75, 0.14) !important; border-radius: 26px !important; background: #ffffff !important; box-shadow: 0 18px 45px rgba(28, 36, 75, 0.10) !important; overflow: visible !important; position: relative !important; z-index: 1 !important; isolation: isolate !important; }\n    .ols-zoom-card.medium { max-width: 820px; }\n    .ols-zoom-card.compact { max-width: 700px; }\n    .ols-zoom-card.wide { max-width: 940px; }\n    .ols-zoom-card.slim { max-width: 600px; }\n    .ols-zoom-card:hover { z-index: 50 !important; }\n    .ols-zoom-card-image { display: flex !important; align-items: center !important; justify-content: center !important; width: 100% !important; min-height: 240px !important; padding: 20px !important; background: #ffffff !important; overflow: visible !important; border-top-left-radius: 26px !important; border-top-right-radius: 26px !important; position: relative !important; z-index: 2 !important; }\n    .ols-zoom-card img.ols-zoomable-img { display: block !important; max-width: 100% !important; height: auto !important; border-radius: 18px !important; cursor: zoom-in !important; pointer-events: auto !important; user-select: none !important; -webkit-user-drag: none !important; transform: translateZ(0) scale(1) !important; transform-origin: center center !important; transition: transform 0.32s ease, box-shadow 0.32s ease, filter 0.32s ease !important; position: relative !important; z-index: 2 !important; }\n    @media (hover: hover) and (pointer: fine) { .ols-zoom-card img.ols-zoomable-img:hover { transform: translateZ(0) scale(1.35) !important; box-shadow: 0 28px 70px rgba(28, 36, 75, 0.34) !important; filter: saturate(1.02) contrast(1.01) !important; z-index: 100 !important; } }\n    .ols-zoom-card-caption { padding: 18px 22px 20px !important; background: linear-gradient(135deg, #ffffff, #f8fbff) !important; border-bottom-left-radius: 26px !important; border-bottom-right-radius: 26px !important; position: relative !important; z-index: 1 !important; }\n    .ols-zoom-card-caption p { margin: 0 !important; color: #5f6b85 !important; font-size: 15px !important; line-height: 1.65 !important; font-weight: 300 !important; font-style: italic !important; font-family: Poppins, Arial, sans-serif !important; }\n    .ols-image-lightbox { position: fixed; inset: 0; z-index: 999999; display: none; align-items: center; justify-content: center; padding: 34px; background: rgba(10, 15, 35, 0.86); backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px); }\n    .ols-image-lightbox.is-open { display: flex; }\n    .ols-image-lightbox-inner { position: relative; width: min(96vw, 1500px); max-height: 92vh; display: flex; align-items: center; justify-content: center; }\n    .ols-image-lightbox-img { display: block; max-width: 100%; max-height: 92vh; height: auto; width: auto; border-radius: 22px; background: #ffffff; box-shadow: 0 32px 90px rgba(0, 0, 0, 0.45); object-fit: contain; }\n    .ols-image-lightbox-close { position: absolute; top: -18px; right: -18px; width: 46px; height: 46px; border: 0; border-radius: 50%; background: #ffffff; color: var(--navy); font-family: Poppins, Arial, sans-serif; font-size: 28px; line-height: 1; font-weight: 700; cursor: pointer; box-shadow: 0 16px 34px rgba(0, 0, 0, 0.28); display: flex; align-items: center; justify-content: center; transition: transform 0.2s ease, background 0.2s ease, color 0.2s ease; }\n    .ols-image-lightbox-close:hover { transform: scale(1.08); background: var(--blue); color: #ffffff; }\n    @media (max-width: 760px) { .ols-zoom-card { border-radius: 22px !important; overflow: hidden !important; } .ols-zoom-card-image { min-height: auto !important; padding: 12px !important; overflow: hidden !important; border-top-left-radius: 22px !important; border-top-right-radius: 22px !important; } .ols-zoom-card img.ols-zoomable-img, .ols-zoom-card img.ols-zoomable-img:hover { transform: none !important; box-shadow: none !important; } .ols-zoom-card-caption { border-bottom-left-radius: 22px !important; border-bottom-right-radius: 22px !important; } .ols-image-lightbox { padding: 16px; } .ols-image-lightbox-inner { width: 100%; max-height: 88vh; } .ols-image-lightbox-img { max-height: 88vh; border-radius: 16px; } .ols-image-lightbox-close { top: 10px; right: 10px; width: 42px; height: 42px; font-size: 26px; } }\n\n\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\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\n    .ols-faq-list { display: grid; gap: 14px; margin-top: 18px; }\n    .ols-faq-item { background: #ffffff; border: 1px solid var(--border); border-radius: 18px; padding: 18px 20px; box-shadow: var(--inner-shadow); }\n    .ols-faq-item h3 { margin: 0 0 8px; font-size: 20px; line-height: 1.3; color: var(--navy); }\n    .ols-faq-item p { margin: 0; font-size: 16px; line-height: 1.65; color: var(--body-text); }\n\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    .ols-course-cta-covalent {\n      width: 100%;\n      margin: 30px 0 24px;\n      font-family: Poppins, Arial, sans-serif;\n    }\n    .ols-course-cta-covalent, .ols-course-cta-covalent * { box-sizing: border-box; }\n    .ols-course-cta-card {\n      overflow: hidden;\n      border-radius: 30px;\n      border: 1px solid var(--border);\n      background: radial-gradient(circle at top left, rgba(37, 99, 235, 0.16), transparent 34%), linear-gradient(135deg, #ffffff 0%, #f8fbff 100%);\n      box-shadow: var(--shadow);\n      padding: 30px;\n    }\n    .ols-course-cta-top {\n      display: grid;\n      grid-template-columns: minmax(260px, 0.9fr) minmax(0, 1.1fr);\n      gap: 28px;\n      align-items: center;\n      margin-bottom: 24px;\n    }\n    .ols-course-cta-image-link { display: block; text-decoration: none; border-radius: 24px; }\n    .ols-course-cta-image {\n      width: 100%;\n      border-radius: 24px;\n      overflow: hidden;\n      border: 1px solid var(--border);\n      background: #ffffff;\n      box-shadow: var(--inner-shadow);\n      transition: transform 0.35s ease, box-shadow 0.35s ease;\n    }\n    .ols-course-cta-image img { width: 100%; height: auto; display: block; transition: transform 0.45s ease; }\n    .ols-course-cta-image-link:hover .ols-course-cta-image { transform: translateY(-8px) scale(1.015); box-shadow: 0 26px 60px rgba(28, 36, 75, 0.18), 0 0 0 1px rgba(37, 99, 235, 0.12); }\n    .ols-course-cta-image-link:hover .ols-course-cta-image img { transform: scale(1.03); }\n    .ols-course-cta-header-row { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 14px; margin-bottom: 18px; }\n    .ols-course-cta-kicker { display: inline-flex; align-items: center; padding: 8px 14px; border-radius: 999px; background: #ffffff; border: 1px solid rgba(37, 99, 235, 0.18); color: var(--blue); font-size: 14px; line-height: 1.2; font-weight: 700; box-shadow: var(--inner-shadow); }\n    .ols-course-cta-covalent h2 { margin: 0 0 14px; font-size: clamp(28px, 3.5vw, 42px); line-height: 1.15; font-weight: 800; letter-spacing: -0.03em; color: #111827; }\n    .ols-course-cta-intro { margin: 0 0 24px; color: var(--body-text); font-size: clamp(16px, 1.4vw, 18px); line-height: 1.7; font-weight: 300; }\n    .ols-course-cta-features { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; margin: 0 0 30px; }\n    .ols-course-feature { background: rgba(255, 255, 255, 0.78); border: 1px solid var(--border); border-radius: 18px; padding: 16px 18px; }\n    .ols-course-feature h3 { margin: 0 0 6px; color: var(--navy); font-size: 18px; line-height: 1.3; font-weight: 800; }\n    .ols-course-feature p { margin: 0; color: var(--body-text); font-size: 15px; line-height: 1.6; font-weight: 300; }\n    .ols-course-cta-bottom { display: flex; justify-content: center; padding-top: 22px; border-top: 1px solid var(--border); }\n    .ols-course-button { display: inline-flex; align-items: center; justify-content: center; padding: 15px 28px; border-radius: 999px; background: var(--navy); color: #ffffff; text-decoration: none; font-size: 16px; line-height: 1.2; font-weight: 800; box-shadow: 0 12px 26px rgba(28, 36, 75, 0.18); transition: transform 0.2s ease, background 0.2s ease, box-shadow 0.2s ease; }\n    .ols-course-button:hover { transform: translateY(-2px); background: var(--blue); color: #ffffff; box-shadow: 0 16px 32px rgba(37, 99, 235, 0.24); }\n    .ols-course-button-top { flex-shrink: 0; padding: 12px 22px; font-size: 15px; }\n\n    .ols-attribution-card {\n      background: linear-gradient(135deg, #ffffff, #f8fbff);\n      border: 1px solid rgba(28, 36, 75, 0.14);\n      border-radius: 28px;\n      box-shadow: 0 18px 45px rgba(28, 36, 75, 0.10);\n      padding: 34px;\n      margin-bottom: 24px;\n      overflow: hidden;\n      font-family: Poppins, Arial, sans-serif;\n      box-sizing: border-box;\n    }\n    .ols-attribution-card, .ols-attribution-card * { box-sizing: border-box; }\n    .ols-attribution-card p { margin: 0; font-size: 14px; line-height: 1.65; font-weight: 300; color: #667085; }\n    .ols-attribution-card strong { font-weight: 700; color: #1C244B; }\n\n    @media (max-width: 1050px) {\n      .ols-main { max-width: none; }\n      .ols-related-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }\n      .ols-course-cta-top { grid-template-columns: 1fr; }\n      .ols-course-cta-image-link { max-width: 520px; margin: 0 auto; }\n    }\n\n    @media (max-width: 760px) {\n      .ols-title-card, .ols-note-card, .ols-h5p-card, .ols-related-card, .ols-faq-card, .ols-attribution-card { padding: 24px 18px; border-radius: 22px; }\n      .ols-note-title { align-items: flex-start; }\n      .ols-related-grid, .ols-course-cta-features { grid-template-columns: 1fr; }\n      .ols-figure-card { border-radius: 22px; }\n      .ols-figure-image { min-height: 210px; padding: 14px; }\n      .ols-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      .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-course-cta-card { padding: 20px; border-radius: 24px; }\n      .ols-course-cta-header-row { align-items: stretch; }\n      .ols-course-button-top, .ols-course-button { width: 100%; }\n    }\n  \n    .ols-figure-placeholder .ols-placeholder-box { border: 2px dashed #c9973a; background: #fffaf0; border-radius: 16px; padding: 26px 22px; font-weight: 700; color: #7a4b12; text-align: center; line-height: 1.6; }\n    .ols-figure-placeholder .ols-figure-image { background: transparent; }\n    .ols-figure-placeholder { background: #ffffff; border: 1px solid rgba(28, 36, 75, 0.12); border-radius: 22px; padding: 14px; margin: 18px 0 6px; }\n    .ols-figure-placeholder .ols-figure-caption p { margin: 10px 0 0; font-size: 14px; color: #667085; text-align: center; }\n\n    \/* inline checks (H5P re-flow, Sep 2026) *\/\n    .ols-h5p-card.ols-h5p-inline { padding: 26px 28px; border-left: 6px solid #7c3aed; }\n    .ols-h5p-card.ols-h5p-inline h2 { font-size: clamp(20px, 2.2vw, 27px); letter-spacing: -0.02em; }\n    .ols-h5p-card.ols-h5p-inline > p { margin: 8px 0 0; }\n    .ols-h5p-card.ols-h5p-inline .ols-h5p-frame { margin-top: 16px; padding: 14px; border-radius: 20px; }\n    .ols-h5p-kicker { display: inline-block; margin-bottom: 10px; padding: 5px 12px; border-radius: 999px; background: #ede9fe; color: #5b21b6; font-size: 12px; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase; }\n    .ols-h5p-card.ols-h5p-recap { border-left-color: #c9973a; background: linear-gradient(135deg, #ffffff 0%, #fff8e8 100%); }\n    .ols-h5p-recap .ols-h5p-kicker { background: #fdf0d2; color: #8a5a00; }\n    @media (max-width: 760px) { .ols-h5p-card.ols-h5p-inline { padding: 20px 16px; } }\n<\/style>\n\n  <aside class=\"ols-sidebar\">\n  <div class=\"ols-sidebar-header\">\n    <h3>Revision Notes<\/h3>\n    <p>A Level Chemistry<\/p>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>4.2.2 Haloalkanes<\/h4>\n\n    <ul class=\"ols-topic-list\">\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/\">4.2.2 Overview<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/reaction-types-mechanisms-and-nucleophiles\/\">Reaction Types, Mechanisms and Nucleophiles<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/halogenoalkanes-naming-classification-and-bonding\/\">Haloalkanes: Naming, Classification and the C\u2013X Bond<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/nucleophilic-substitution-reactions\/\">Nucleophilic Substitution Reactions<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/rates-of-hydrolysis-and-bond-enthalpy\/\">Rates of Hydrolysis and Bond Enthalpy<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/\">CFCs and the Ozone Layer<\/a>\n      <\/li>\n    <\/ul>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>Other Sections<\/h4>\n\n    <ul class=\"ols-topic-list\">\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-1-alcohols\/\">4.2.1 Alcohols<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-4-analytical-techniques\/\">4.2.4 Analytical Techniques<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-1-3-alkenes\/\">4.1.3 Alkenes<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-1-2-alkanes\/\">4.1.2 Alkanes<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-1-1-basic-concepts-of-organic-chemistry\/\">4.1.1 Basic Concepts of Organic Chemistry<\/a>\n      <\/li>\n    <\/ul>\n  <\/div>\n<\/aside>\n\n<script>\r\n(function() {\r\n  function normalisePath(path) {\r\n    return String(path || '')\r\n      .split('?')[0]\r\n      .split('#')[0]\r\n      .replace(\/\\\/+$\/, '')\r\n      .toLowerCase();\r\n  }\r\n\r\n  function highlightActive() {\r\n    var sidebar = document.querySelector('.ols-sidebar');\r\n    if (!sidebar) return false;\r\n\r\n    var currentPath = normalisePath(window.location.pathname);\r\n    var links = 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  <main class=\"ols-main\">\n      <nav class=\"ols-breadcrumbs\" aria-label=\"Breadcrumb\">\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\">Revision Notes<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\">A Level Chemistry<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/\">OCR<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/\">4.2.2 Haloalkanes<\/a> \/\n<span>CFCs and the Ozone Layer<\/span>\n<\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>CFCs and the Ozone Layer<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to ozone and CFCs: why ozone in the upper atmosphere is beneficial, how UV radiation breaks C\u2013Cl bonds to form chlorine radicals, the radical equations for the catalysed decomposition of ozone, and the evidence, legislation and chlorine-free alternatives.<\/p>\n\n        <div class=\"ols-badges\">\n<div class=\"ols-badge\">Paper 2 and 3<\/div>\n<div class=\"ols-badge\">4.2.2: Haloalkanes<\/div>\n<div class=\"ols-badge\">H432\/02 and H432\/03<\/div>\n<\/div>\n\n        <div class=\"ols-author\">\n\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\n      <h2 class=\"ols-author-title\">\n        Written by:<br><span>Dr. Mohammed Al-Fatah<\/span>\n      <\/h2>\n\n      <p class=\"ols-author-description\">\n        Chemistry specialist revision notes for A Level Chemistry.\n      <\/p>\n\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\n    <\/div>\n\n  <\/div>\n      <\/header>\n\n      <article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">1<\/div>\n<h2>Ozone in the Upper Atmosphere<\/h2>\n<\/div>\n<p><strong>Ozone<\/strong>, O\u2083, forms a layer in the upper atmosphere where it absorbs much of the ultraviolet radiation arriving from the Sun. That absorption protects living things from the skin cancers, eye damage and crop damage that high-energy UV causes, so the ozone layer is beneficial. Ozone near the ground is different: there it is a pollutant formed in photochemical smog.<\/p>\n<p><strong>Chlorofluorocarbons<\/strong>, CFCs such as CF\u2082Cl\u2082 and CFCl\u2083, were used as refrigerants, aerosol propellants, solvents and foam-blowing agents because they are unreactive, non-flammable and non-toxic. That same unreactivity lets them survive long enough to drift up into the stratosphere.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Key idea:<\/strong> Ozone high up is protective because it absorbs UV; CFCs reach it because they are too stable to be broken down lower in the atmosphere.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">2<\/div>\n<h2>Chlorine Radicals Destroy Ozone<\/h2>\n<\/div>\n<p>In the upper atmosphere ultraviolet radiation has enough energy to break the <strong>C\u2013Cl bond<\/strong> in a CFC homolytically, forming a chlorine radical: CF\u2082Cl\u2082 \u2192 CF\u2082Cl\u2022 + Cl\u2022. The C\u2013F bond is stronger and is not broken. The chlorine radical then destroys ozone in two propagation steps: Cl\u2022 + O\u2083 \u2192 ClO\u2022 + O\u2082 and ClO\u2022 + O\u2083 \u2192 2O\u2082 + Cl\u2022. Adding the two steps and cancelling the radicals gives the overall reaction <strong>2O\u2083 \u2192 3O\u2082<\/strong>. The chlorine radical is regenerated, so it acts as a <strong>catalyst<\/strong>, providing a route with a lower activation energy, and one radical can destroy many thousands of ozone molecules before it is removed.<\/p>\n<p>Other radicals do the same. Nitrogen monoxide from aircraft exhausts catalyses ozone breakdown by NO\u2022 + O\u2083 \u2192 NO\u2082\u2022 + O\u2082 and NO\u2082\u2022 + O \u2192 NO\u2022 + O\u2082, with the same overall result.<\/p>\n<div class=\"ols-zoom-card\">\n<div class=\"ols-zoom-card-image\">\n<a class=\"ols-lightbox-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/alcohols-halogenoalkanes-spectra-ozone.jpg\" aria-label=\"Open image full screen\">\n<img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/alcohols-halogenoalkanes-spectra-ozone.jpg\" alt=\"Chlorine radicals from CFCs catalysing the breakdown of ozone, with the evidence and chlorine-free alternatives\">\n<\/a>\n<\/div>\n<div class=\"ols-zoom-card-caption\"><p>UV breaks a C\u2013Cl bond in a CFC; the chlorine radical then cycles through two steps that turn ozone into oxygen and is regenerated.<\/p><\/div>\n<\/div>\n<div class=\"ols-key-box\">\n<p><strong>Exam focus:<\/strong> Both propagation equations, the overall equation 2O\u2083 \u2192 3O\u2082, and the word &#8220;catalyst&#8221; with the reason: the chlorine radical is regenerated.<\/p>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Check: The Ozone Cycle<\/h2>\n<p>Write and use the radical equations for a scenario not given above.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"964\"><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">3<\/div>\n<h2>Evidence, Legislation and Alternatives<\/h2>\n<\/div>\n<p>Scientific evidence from different research groups, gathered by satellite and by balloon measurements, showed that CFCs were responsible for the fall in ozone. The evidence led to legislation, the Montreal Protocol of 1987, which banned the manufacture and use of CFCs. Chemists then developed <strong>chlorine-free alternatives<\/strong>: hydrofluorocarbons (HFCs) such as CH\u2082FCF\u2083 are now used in refrigerators and air conditioning. They contain no C\u2013Cl bond, and the C\u2013F bond is too strong to be broken by UV, so they do not produce ozone-destroying radicals. Hydrocarbons such as butane are used as propellants.<\/p>\n<p>The ozone layer is recovering slowly, because CFCs already released stay in the atmosphere for decades. The story is used in exams as an example of how scientific evidence, gathered and checked by different groups, leads to legislation and to new chemistry.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Exam wording:<\/strong> &#8220;Chlorine-free alternatives such as HFCs contain C\u2013F bonds that are not broken by UV radiation, so no chlorine radicals form.&#8221;<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">4<\/div>\n<h2>Common Exam Points<\/h2>\n<\/div>\n<h3>Say<\/h3><p>&#8220;UV breaks the C\u2013Cl bond homolytically to form a chlorine radical.&#8221; &#8220;Cl\u2022 is regenerated so it is a catalyst.&#8221; &#8220;2O\u2083 \u2192 3O\u2082 overall.&#8221;<\/p>\n<h3>Do not say<\/h3><p>&#8220;Ozone causes global warming&#8221; (that is carbon dioxide and infrared). &#8220;The C\u2013F bond breaks.&#8221;<\/p>\n<h3>Watch for<\/h3><p>Radicals must be written with the dot: Cl\u2022 and ClO\u2022, not Cl and ClO.<\/p>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Check: Evidence and Alternatives<\/h2>\n<p>Evaluate replacement compounds that are not the examples used above.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-965\" class=\"h5p-iframe\" data-content-id=\"965\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Alcohols, Halogenoalkanes and Spectra Summary: Evidence and Alternatives\"><\/iframe><\/div><\/div>\n<\/section>\n<section class=\"ols-faq-card\">\n<h2>FAQs<\/h2>\n<p>Use these quick answers to check the ozone chemistry.<\/p>\n\n<div class=\"ols-faq-list\">\n<div class=\"ols-faq-item\">\n<h3>Why is ozone good high up but bad near the ground?<\/h3>\n<p>In the upper atmosphere it absorbs harmful UV radiation. Near the ground it is a pollutant formed in photochemical smog that damages lungs and plants.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>Why does UV break the C\u2013Cl bond and not the C\u2013F bond?<\/h3>\n<p>The C\u2013F bond is much stronger (about 467 kJ mol\u207b\u00b9 against 346 for C\u2013Cl), so UV photons do not have enough energy to break it.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>Why is the chlorine radical called a catalyst?<\/h3>\n<p>It is regenerated at the end of the two-step cycle, so it is not used up and one radical can destroy thousands of ozone molecules while providing a lower-energy route for 2O\u2083 \u2192 3O\u2082.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>How do the two equations give the overall equation?<\/h3>\n<p>Add them: Cl\u2022 + O\u2083 + ClO\u2022 + O\u2083 \u2192 ClO\u2022 + O\u2082 + 2O\u2082 + Cl\u2022. The Cl\u2022 and ClO\u2022 cancel, leaving 2O\u2083 \u2192 3O\u2082.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>Why are HFCs safe for the ozone layer?<\/h3>\n<p>They contain no C\u2013Cl bonds, and their C\u2013F bonds are too strong to be broken by UV, so no radicals that destroy ozone are formed.<\/p>\n<\/div>\n<\/div>\n<\/section>\n<section class=\"ols-related-card\">\n<h2>Related 4.2.2 Haloalkanes Pages<\/h2>\n<p>Use these pages to connect the ideas across 4.2.2 Haloalkanes and the rest of the course.<\/p>\n<div class=\"ols-related-grid\">\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/reaction-types-mechanisms-and-nucleophiles\/\">Reaction Types, Mechanisms and Nucleophiles<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/halogenoalkanes-naming-classification-and-bonding\/\">Haloalkanes: Naming, Classification and the C\u2013X Bond<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/nucleophilic-substitution-reactions\/\">Nucleophilic Substitution Reactions<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/rates-of-hydrolysis-and-bond-enthalpy\/\">Rates of Hydrolysis and Bond Enthalpy<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/\">4.2.2 Haloalkanes Overview<\/a>\n<\/div>\n<\/section>\n<section class=\"ols-attribution-card\">\n        <p><strong>Copyright and author footprint:<\/strong> This OLS revision page was written for Online Learning System by <strong>Dr. Mohammed Al-Fatah<\/strong>. It is designed for A Level Chemistry revision and should not be copied or redistributed without permission.<\/p>\n      <\/section>\n\n      <div class=\"ols-image-lightbox\" id=\"olsImageLightboxNatureCovalentBonding9ch0\" aria-hidden=\"true\" role=\"dialog\" aria-modal=\"true\" aria-label=\"Expanded revision image\">\n        <div class=\"ols-image-lightbox-inner\">\n          <button class=\"ols-image-lightbox-close\" type=\"button\" aria-label=\"Close enlarged image\">\u00d7<\/button>\n          <img decoding=\"async\" class=\"ols-image-lightbox-img\" src=\"\" alt=\"\">\n        <\/div>\n      <\/div>\n\n      <script>\n        (function(){\n          var page = document.querySelector(\".ols-nature-of-covalent-bonding-9ch0-page\");\n          if (!page) { return; }\n          var lightbox = page.querySelector(\"#olsImageLightboxNatureCovalentBonding9ch0\");\n          if (!lightbox) { return; }\n          var lightboxImage = lightbox.querySelector(\".ols-image-lightbox-img\");\n          var closeButton = lightbox.querySelector(\".ols-image-lightbox-close\");\n          var clickableImages = page.querySelectorAll(\"img.ols-lightbox-target\");\n          function openLightbox(image) {\n            lightboxImage.src = image.currentSrc || image.src;\n            lightboxImage.alt = image.alt || \"Expanded revision image\";\n            lightbox.classList.add(\"is-open\");\n            lightbox.setAttribute(\"aria-hidden\", \"false\");\n            if (!document.body.dataset.olsPreviousOverflow) {\n              document.body.dataset.olsPreviousOverflow = document.body.style.overflow || \"default\";\n            }\n            document.body.style.overflow = \"hidden\";\n          }\n          function closeLightbox() {\n            lightbox.classList.remove(\"is-open\");\n            lightbox.setAttribute(\"aria-hidden\", \"true\");\n            lightboxImage.src = \"\";\n            if (document.body.dataset.olsPreviousOverflow) {\n              document.body.style.overflow = document.body.dataset.olsPreviousOverflow === \"default\" ? \"\" : document.body.dataset.olsPreviousOverflow;\n              delete document.body.dataset.olsPreviousOverflow;\n            }\n          }\n          clickableImages.forEach(function(image){\n            image.addEventListener(\"click\", function(event){\n              event.preventDefault();\n              event.stopPropagation();\n              openLightbox(image);\n            });\n          });\n          closeButton.addEventListener(\"click\", closeLightbox);\n          lightbox.addEventListener(\"click\", function(event){ if (event.target === lightbox) { closeLightbox(); } });\n          document.addEventListener(\"keydown\", function(event){ if (event.key === \"Escape\" && lightbox.classList.contains(\"is-open\")) { closeLightbox(); } });\n        })();\n      <\/script>\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\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/#webpage\",\n      \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/\",\n      \"name\": \"CFCs and the Ozone Layer | 4.2.2 Haloalkanes | Online Learning System\",\n      \"description\": \"OCR A A Level Chemistry revision notes on CFCs and the ozone layer: chlorine radicals, the equations for ozone decomposition, the catalytic cycle, legislation and HFC alternatives.\",\n      \"isPartOf\": {\n        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/#website\"\n      },\n      \"breadcrumb\": {\n        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/#breadcrumb\"\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\": \"BreadcrumbList\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/#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 Chemistry\"\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\/ocr-a\/\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/\",\n            \"name\": \"OCR\"\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\/ocr-a\/4-2-2-haloalkanes\/\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/\",\n            \"name\": \"4.2.2 Haloalkanes\"\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\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/\",\n            \"name\": \"CFCs and the Ozone Layer\"\n          }\n        }\n      ]\n    },\n    {\n      \"@type\": \"Course\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/#course\",\n      \"name\": \"CFCs and the Ozone Layer\",\n      \"description\": \"OCR A A Level Chemistry revision notes on CFCs and the ozone layer: chlorine radicals, the equations for ozone decomposition, the catalytic cycle, legislation and HFC alternatives.\",\n      \"provider\": {\n        \"@type\": \"Organization\",\n        \"name\": \"Online Learning System\",\n        \"url\": \"https:\/\/www.onlinelearningsystem.net\/\"\n      },\n      \"educationalLevel\": \"A Level\",\n      \"about\": [\n        \"Alcohols\",\n        \"Halogenoalkanes\",\n        \"Nucleophilic substitution\",\n        \"Elimination\",\n        \"Oxidation of alcohols\",\n        \"Mass spectrometry\",\n        \"Infrared spectroscopy\"\n      ],\n      \"hasCourseInstance\": {\n        \"@type\": \"CourseInstance\",\n        \"courseMode\": \"Online\"\n      }\n    },\n    {\n      \"@type\": \"ItemList\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/cfcs-and-the-ozone-layer\/#relatedtopics\",\n      \"name\": \"Related 4.2.2 Haloalkanes Pages\",\n      \"itemListElement\": [\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 1,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Reaction Types, Mechanisms and Nucleophiles\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/reaction-types-mechanisms-and-nucleophiles\/\",\n            \"description\": \"OCR A A Level Chemistry revision notes on organic reaction types and mechanisms: addition, elimination, substitution, oxidation, reduction, hydrolysis, polymerisation, curly arrows, heterolytic fission, electrophiles, nucleophiles and bond polarity.\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 2,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Haloalkanes: Naming, Classification and the C\u2013X Bond\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/halogenoalkanes-naming-classification-and-bonding\/\",\n            \"description\": \"OCR A A Level Chemistry revision notes on haloalkanes: nomenclature and formulae, primary, secondary and tertiary, the polar carbon\u2013halogen bond, bond enthalpies and uses.\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 3,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Nucleophilic Substitution Reactions\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/nucleophilic-substitution-reactions\/\",\n            \"description\": \"OCR A A Level Chemistry revision notes on nucleophilic substitution of haloalkanes: hydroxide, water, ammonia and cyanide as nucleophiles, conditions, products and the curly-arrow mechanism.\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 4,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Rates of Hydrolysis and Bond Enthalpy\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/ocr-a\/4-2-2-haloalkanes\/rates-of-hydrolysis-and-bond-enthalpy\/\",\n            \"description\": \"OCR A A Level Chemistry revision notes on rates of hydrolysis of haloalkanes: the silver nitrate experiment, precipitate colours, bond enthalpy trend for C\u2013Cl, C\u2013Br and C\u2013I, and primary, secondary and tertiary comparison.\"\n          }\n        }\n      ]\n    }\n  ]\n}\n<\/script>\n    <\/main>\n<\/section>\n","protected":false},"excerpt":{"rendered":"<p>Revision Notes \/ A Level Chemistry \/ OCR \/ 4.2.2 Haloalkanes \/ CFCs and the Ozone Layer CFCs and the Ozone Layer A concise revision guide to ozone and CFCs: why ozone in the upper atmosphere is beneficial, how UV radiation breaks C\u2013Cl bonds to form chlorine radicals, the radical equations for the catalysed decomposition [&hellip;]<\/p>\n","protected":false},"author":12,"featured_media":0,"parent":10960,"menu_order":4,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-10970","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/10970","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=10970"}],"version-history":[{"count":2,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/10970\/revisions"}],"predecessor-version":[{"id":11224,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/10970\/revisions\/11224"}],"up":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/10960"}],"wp:attachment":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/media?parent=10970"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}