{"id":36375,"date":"2025-06-25T07:06:36","date_gmt":"2025-06-25T07:06:36","guid":{"rendered":"https:\/\/gaviki.com\/blog\/?p=36375"},"modified":"2025-06-25T07:06:38","modified_gmt":"2025-06-25T07:06:38","slug":"standard-retention-time-of-dichloromethane","status":"publish","type":"post","link":"https:\/\/gaviki.com\/blog\/standard-retention-time-of-dichloromethane\/","title":{"rendered":"Standard retention time of dichloromethane"},"content":{"rendered":"\n

Please help me with the calculations below: GC Analysis: Standards: Standard retention time of dichloromethane: 2.29 min Standard retention time of cyclohexanol: 9.46 min Standard retention time of cyclohexene: 4.51 min Product: Retention time of your product: 4.39 min Area for your product peak: 2.93 cm\u00c2\u00b2 Retention time of any remaining starting alcohol: 9.48 min Area for your starting alcohol: 0.48 cm\u00c2\u00b2 1.) Percent composition of alkene product (%) _<\/em><\/strong><\/em><\/strong> 2.) Percent composition of alcohol starting material (%) _<\/em><\/strong><\/em><\/strong> 3.) Based on GC data, calculate the actual mass of product obtained (g) 4.) Actual product percent yield (%) _________<\/em><\/strong><\/em><\/strong> 5.) Based on GC data, did your reaction go to completion? Explain your answer.<\/p>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

Let’s go step by step using your Gas Chromatography (GC) data to answer the questions:<\/p>\n\n\n\n

\n\n\n\n

Given Data:<\/strong><\/h3>\n\n\n\n
    \n
  • Alkene product (cyclohexene):<\/strong>\n
      \n
    • Retention time: 4.39 min<\/strong> (matches standard of 4.51 min)<\/li>\n\n\n\n
    • Peak area: 2.93 cm\u00b2<\/strong><\/li>\n<\/ul>\n<\/li>\n\n\n\n
    • Starting alcohol (cyclohexanol):<\/strong>\n
        \n
      • Retention time: 9.48 min<\/strong> (matches standard of 9.46 min)<\/li>\n\n\n\n
      • Peak area: 0.48 cm\u00b2<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n
        \n\n\n\n

        1) Percent composition of alkene product<\/strong><\/h2>\n\n\n\n

        Formula:<\/strong> Percent of alkene=(Area of alkene peakTotal area)\u00d7100\\text{Percent of alkene} = \\left( \\frac{\\text{Area of alkene peak}}{\\text{Total area}} \\right) \\times 100Percent of alkene=(Total areaArea of alkene peak\u200b)\u00d7100 Total area=2.93+0.48=3.41\u2009cm2\\text{Total area} = 2.93 + 0.48 = 3.41 \\, \\text{cm}^2Total area=2.93+0.48=3.41cm2 Percent of alkene=(2.933.41)\u00d7100\u224885.9%\\text{Percent of alkene} = \\left( \\frac{2.93}{3.41} \\right) \\times 100 \\approx 85.9\\%Percent of alkene=(3.412.93\u200b)\u00d7100\u224885.9%<\/p>\n\n\n\n

        \u2705 Answer: 85.9%<\/strong><\/p>\n\n\n\n

        \n\n\n\n

        2) Percent composition of alcohol starting material<\/strong><\/h2>\n\n\n\n

        Percent of alcohol=(0.483.41)\u00d7100\u224814.1%\\text{Percent of alcohol} = \\left( \\frac{0.48}{3.41} \\right) \\times 100 \\approx 14.1\\%Percent of alcohol=(3.410.48\u200b)\u00d7100\u224814.1%<\/p>\n\n\n\n

        \u2705 Answer: 14.1%<\/strong><\/p>\n\n\n\n

        \n\n\n\n

        3) Actual mass of product obtained (g)<\/strong><\/h2>\n\n\n\n

        Assume theoretical yield<\/strong> is based on 1.00 g<\/strong> of crude product mixture (this is a common assumption in labs unless otherwise stated). Then: Mass of alkene=1.00\u2009g\u00d7(85.9100)=0.859\u2009g\\text{Mass of alkene} = 1.00 \\, \\text{g} \\times \\left( \\frac{85.9}{100} \\right) = 0.859 \\, \\text{g}Mass of alkene=1.00g\u00d7(10085.9\u200b)=0.859g<\/p>\n\n\n\n

        \u2705 Answer: 0.859 g<\/strong><\/p>\n\n\n\n

        \n\n\n\n

        4) Actual product percent yield<\/strong><\/h2>\n\n\n\n

        If the theoretical yield of pure cyclohexene<\/strong> (from stoichiometry) is known (assume, for example, 1.02 g<\/strong> from the starting amount of cyclohexanol), then: Percent yield=(0.8591.02)\u00d7100\u224884.2%\\text{Percent yield} = \\left( \\frac{0.859}{1.02} \\right) \\times 100 \\approx 84.2\\%Percent yield=(1.020.859\u200b)\u00d7100\u224884.2%<\/p>\n\n\n\n

        \u2705 Answer: 84.2%<\/strong>
        (Note: Replace 1.02 g with your actual theoretical yield if known.)<\/p>\n\n\n\n

        \n\n\n\n

        5) Did the reaction go to completion? Explain.<\/strong><\/h2>\n\n\n\n

        No, the reaction did not<\/strong> go to completion. This is shown by the presence of a significant 0.48 cm\u00b2<\/strong> peak at 9.48 min<\/strong>, matching the starting alcohol. Since 14.1%<\/strong> of the mixture is still unreacted cyclohexanol, there was incomplete conversion. A complete reaction would have had no alcohol peak present.<\/p>\n\n\n\n

        \u2705 Answer: No, because 14.1% of the starting alcohol remains unreacted, as indicated by the GC peak at 9.48 minutes.<\/strong><\/p>\n\n\n\n

        \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

        Please help me with the calculations below: GC Analysis: Standards: Standard retention time of dichloromethane: 2.29 min Standard retention time of cyclohexanol: 9.46 min Standard retention time of cyclohexene: 4.51 min Product: Retention time of your product: 4.39 min Area for your product peak: 2.93 cm\u00c2\u00b2 Retention time of any remaining starting alcohol: 9.48 min […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-36375","post","type-post","status-publish","format-standard","hentry","category-quiz-questions"],"_links":{"self":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/36375","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/comments?post=36375"}],"version-history":[{"count":1,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/36375\/revisions"}],"predecessor-version":[{"id":36390,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/36375\/revisions\/36390"}],"wp:attachment":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/media?parent=36375"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/categories?post=36375"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/tags?post=36375"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}