{"id":256260,"date":"2025-07-16T08:19:56","date_gmt":"2025-07-16T08:19:56","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=256260"},"modified":"2025-07-16T08:19:58","modified_gmt":"2025-07-16T08:19:58","slug":"butane-c4h10-g-ihf-125-7-kj-mol-combusts-in-the-presence-of-oxygen-to-form-co2-g-ihf-393-5-kj-mol-and-h2o-g-ihf-241-82-kj-mol-in-the-reaction","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/16\/butane-c4h10-g-ihf-125-7-kj-mol-combusts-in-the-presence-of-oxygen-to-form-co2-g-ihf-393-5-kj-mol-and-h2o-g-ihf-241-82-kj-mol-in-the-reaction\/","title":{"rendered":"Butane (C4H10) (g), (\u00ce\u201dHf = -125.7 kJ\/mol), combusts in the presence of oxygen to form CO2 (g) (\u00ce\u201dHf = -393.5 kJ\/mol), and H2O (g) (\u00ce\u201dHf = -241.82 kJ\/mol) in the reaction"},"content":{"rendered":"\n

Butane (C4H10) (g), (\u00ce\u201dHf = -125.7 kJ\/mol), combusts in the presence of oxygen to form CO2 (g) (\u00ce\u201dHf = -393.5 kJ\/mol), and H2O (g) (\u00ce\u201dHf = -241.82 kJ\/mol) in the reaction: 2C4H10 (g) + 13O2 (g) \u00e2\u2020\u2019 8CO2 + 10H2O (g). What is the enthalpy of combustion, per mole, of butane<\/p>\n\n\n\n

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

Correct answer:<\/strong>
The enthalpy of combustion per mole of butane is -2657.3 kJ\/mol<\/strong>.<\/p>\n\n\n\n

\n\n\n\n

Explanation:<\/strong>
To find the enthalpy of combustion of butane, we use the standard enthalpies of formation (\u0394Hf) and apply Hess’s Law. The combustion reaction is:<\/p>\n\n\n\n

2C4H10 (g) + 13O2 (g) \u2192 8CO2 (g) + 10H2O (g)<\/strong><\/p>\n\n\n\n

The standard enthalpy of formation (\u0394Hf) values are:<\/p>\n\n\n\n

    \n
  • C4H10 (g): -125.7 kJ\/mol<\/li>\n\n\n\n
  • CO2 (g): -393.5 kJ\/mol<\/li>\n\n\n\n
  • H2O (g): -241.82 kJ\/mol<\/li>\n\n\n\n
  • O2 (g): 0 kJ\/mol (because it is an element in its standard state)<\/li>\n<\/ul>\n\n\n\n

    We use this formula:<\/p>\n\n\n\n

    \u0394Hrxn = [\u03a3\u0394Hf (products)] – [\u03a3\u0394Hf (reactants)]<\/strong><\/p>\n\n\n\n

    Step 1: Calculate \u0394Hf of products<\/strong><\/p>\n\n\n\n

      \n
    • 8 mol CO2 \u00d7 (-393.5 kJ\/mol) = -3148.0 kJ<\/li>\n\n\n\n
    • 10 mol H2O \u00d7 (-241.82 kJ\/mol) = -2418.2 kJ
      Total products enthalpy = -3148.0 + (-2418.2) = -5566.2 kJ<\/strong><\/li>\n<\/ul>\n\n\n\n

      Step 2: Calculate \u0394Hf of reactants<\/strong><\/p>\n\n\n\n

        \n
      • 2 mol C4H10 \u00d7 (-125.7 kJ\/mol) = -251.4 kJ<\/li>\n\n\n\n
      • 13 mol O2 \u00d7 0 = 0
        Total reactants enthalpy = -251.4 kJ<\/strong><\/li>\n<\/ul>\n\n\n\n

        Step 3: Find \u0394Hrxn<\/strong>
        \u0394Hrxn = -5566.2 – (-251.4) = -5314.8 kJ<\/strong> for 2 moles of butane<\/p>\n\n\n\n

        Step 4: Per mole of butane<\/strong>
        -5314.8 kJ \u00f7 2 mol = -2657.4 kJ\/mol<\/strong><\/p>\n\n\n\n

        Rounded to one decimal place: -2657.3 kJ\/mol<\/strong><\/p>\n\n\n\n

        This negative value means the reaction is exothermic<\/strong>, releasing a large amount of energy. Combustion reactions of hydrocarbons like butane are commonly used in fuels due to this high energy output. The energy is mainly released as heat, which makes butane a good candidate for heating and cooking purposes.<\/p>\n\n\n\n

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

        Butane (C4H10) (g), (\u00ce\u201dHf = -125.7 kJ\/mol), combusts in the presence of oxygen to form CO2 (g) (\u00ce\u201dHf = -393.5 kJ\/mol), and H2O (g) (\u00ce\u201dHf = -241.82 kJ\/mol) in the reaction: 2C4H10 (g) + 13O2 (g) \u00e2\u2020\u2019 8CO2 + 10H2O (g). What is the enthalpy of combustion, per mole, of butane The Correct Answer and […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-256260","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/256260","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=256260"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/256260\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=256260"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=256260"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=256260"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}