{"id":206686,"date":"2025-04-08T06:35:05","date_gmt":"2025-04-08T06:35:05","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=206686"},"modified":"2025-04-08T06:35:09","modified_gmt":"2025-04-08T06:35:09","slug":"free-energy-is-often-given-in-units-of-kj-mol-or-kcal-mol","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/04\/08\/free-energy-is-often-given-in-units-of-kj-mol-or-kcal-mol\/","title":{"rendered":"Free energy is often given in units of kJ\/mol or kcal\/mol"},"content":{"rendered":"\n

Free energy is often given in units of kJ\/mol or kcal\/mol. One kilocalorie is equal to 4,186.8 joules. A particular reaction has a standard free energy change of -30.5 kJ\/mol. What is the standard free energy change in units of kcal\/mol? (Give your answer as a numeral only with one decimal place.)<\/p>\n\n\n\n

The correct answer and explanation is :<\/strong><\/mark><\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The correct answer is: -7.3<\/strong><\/p>\n\n\n\n

Here’s a detailed explanation:<\/p>\n\n\n\n

In thermodynamics, the standard free energy change (\u0394G\u00b0) is often expressed in kilojoules per mole (kJ\/mol) or kilocalories per mole (kcal\/mol). These units are used to describe the amount of energy associated with chemical reactions, especially whether the reaction releases or absorbs energy under standard conditions.<\/p>\n\n\n\n

In this problem, we\u2019re given a standard free energy change of -30.5 kJ\/mol<\/strong> and asked to convert this to kcal\/mol. To do this, we use the conversion factor:<\/p>\n\n\n\n

1 kilocalorie (kcal) = 4.1868 kilojoules (kJ)<\/strong><\/p>\n\n\n\n

To convert kilojoules to kilocalories, divide the number of kilojoules by the conversion factor:<\/p>\n\n\n\n

[
\\frac{-30.5 \\text{ kJ\/mol}}{4.1868 \\text{ kJ\/kcal}} \\approx -7.3 \\text{ kcal\/mol}
]<\/p>\n\n\n\n

This means the reaction releases 7.3 kilocalories of energy per mole of substance under standard conditions. The negative sign indicates that this is an exergonic<\/strong> reaction \u2014 energy is released, making the process spontaneous<\/strong> under standard conditions.<\/p>\n\n\n\n

Understanding the unit conversion is crucial in scientific disciplines, especially biochemistry, where ATP hydrolysis (a key energy-releasing reaction in cells) has a standard free energy change of approximately -30.5 kJ\/mol \u2014 just like in this problem. Converting this to kcal\/mol helps scientists interpret energy changes in units more commonly used in nutrition and biology.<\/p>\n\n\n\n


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

Free energy is often given in units of kJ\/mol or kcal\/mol. One kilocalorie is equal to 4,186.8 joules. A particular reaction has a standard free energy change of -30.5 kJ\/mol. What is the standard free energy change in units of kcal\/mol? (Give your answer as a numeral only with one decimal place.) The correct answer […]<\/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-206686","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/206686","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=206686"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/206686\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=206686"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=206686"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=206686"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}