{"id":236163,"date":"2025-06-16T05:34:05","date_gmt":"2025-06-16T05:34:05","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=236163"},"modified":"2025-06-16T05:34:07","modified_gmt":"2025-06-16T05:34:07","slug":"the-enthalpy-change-for-which-reaction-depicted-below-is-equivalent-to-the-standard-enthalpy-of-formation-for-sodium-chloride","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/16\/the-enthalpy-change-for-which-reaction-depicted-below-is-equivalent-to-the-standard-enthalpy-of-formation-for-sodium-chloride\/","title":{"rendered":"The enthalpy change for which reaction depicted below is equivalent to the standard enthalpy of formation for sodium chloride"},"content":{"rendered":"\n<p>The enthalpy change for which reaction depicted below is equivalent to the standard enthalpy of formation for sodium chloride? A. Na+ (aq) + Cl- (aq) \u2192 NaCl (s) B. Na+ (aq) + Cl2 (aq) \u2192 NaCl (aq) C. 2Na (s) + Cl2 (g) \u2192 2NaCl (s) D. Na (s) + \u00bd Cl2 (g) \u2192 NaCl (s)<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-0-color\">The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n<p><strong>Correct Answer: D. Na (s) + \u00bd Cl\u2082 (g) \u2192 NaCl (s)<\/strong><\/p>\n\n\n\n<p><strong>Explanation:<\/strong><\/p>\n\n\n\n<p>The <strong>standard enthalpy of formation (\u0394H\u00b0f)<\/strong> of a compound is defined as the <strong>enthalpy change when one mole of a compound is formed from its elements in their standard states under standard conditions<\/strong> (298 K and 1 atm pressure). This process involves the formation of one mole of a compound from its <strong>constituent elements in their most stable forms<\/strong> at standard state.<\/p>\n\n\n\n<p>In the case of <strong>sodium chloride (NaCl)<\/strong>, the relevant elements involved are:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Sodium (Na)<\/strong> in its standard state: a solid metal, denoted as <strong>Na (s)<\/strong>.<\/li>\n\n\n\n<li><strong>Chlorine (Cl\u2082)<\/strong> in its standard state: a diatomic gas, denoted as <strong>Cl\u2082 (g)<\/strong>.<\/li>\n<\/ul>\n\n\n\n<p>Since the goal is to form <strong>one mole<\/strong> of <strong>NaCl (s)<\/strong> from the elements in their standard states, the reaction must use:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>1 mole of sodium (Na)<\/strong> solid.<\/li>\n\n\n\n<li><strong>\u00bd mole of chlorine gas (Cl\u2082)<\/strong>, because chlorine exists as Cl\u2082 molecules and each NaCl requires only one Cl atom.<\/li>\n<\/ul>\n\n\n\n<p>Therefore, the correct reaction that corresponds to the standard enthalpy of formation is:<\/p>\n\n\n\n<p><strong>Na (s) + \u00bd Cl\u2082 (g) \u2192 NaCl (s)<\/strong><\/p>\n\n\n\n<p>This reaction satisfies all criteria:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Reactants are in standard elemental forms.<\/li>\n\n\n\n<li>Exactly one mole of product (NaCl) is formed.<\/li>\n\n\n\n<li>No other substances are present.<\/li>\n<\/ul>\n\n\n\n<p>Option C is similar but forms <strong>2 moles<\/strong> of NaCl, which does not represent the formation of <strong>one mole<\/strong> and therefore does not match the definition of standard enthalpy of formation.<\/p>\n\n\n\n<p>Option A and B involve ions or aqueous states, not elemental forms, and thus do not reflect formation directly from standard-state elements.<\/p>\n\n\n\n<p>Hence, option <strong>D<\/strong> accurately represents the enthalpy of formation for sodium chloride.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/06\/learnexams-banner8-678.jpeg\" alt=\"\" class=\"wp-image-236164\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>The enthalpy change for which reaction depicted below is equivalent to the standard enthalpy of formation for sodium chloride? A. Na+ (aq) + Cl- (aq) \u2192 NaCl (s) B. Na+ (aq) + Cl2 (aq) \u2192 NaCl (aq) C. 2Na (s) + Cl2 (g) \u2192 2NaCl (s) D. Na (s) + \u00bd Cl2 (g) \u2192 NaCl [&hellip;]<\/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-236163","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/236163","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=236163"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/236163\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=236163"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=236163"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=236163"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}