{"id":257069,"date":"2025-07-16T17:52:06","date_gmt":"2025-07-16T17:52:06","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=257069"},"modified":"2025-07-16T17:52:08","modified_gmt":"2025-07-16T17:52:08","slug":"the-freezing-point-depression-constant-kf-of-benzene-is-5-12-k-kg-mol-1","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/16\/the-freezing-point-depression-constant-kf-of-benzene-is-5-12-k-kg-mol-1\/","title":{"rendered":"The freezing point depression constant (Kf) of benzene is 5.12 K kg mol-1"},"content":{"rendered":"\n<p>The freezing point depression constant (Kf) of benzene is 5.12 K kg mol-1. The freezing point depression for the solution of molality 0.078 m containing a non-electrolyte solute in benzene is (rounded off to two decimal places):<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-1-color\">The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n<p>To calculate the freezing point depression (\u0394Tf), we use the formula:\u0394Tf=Kf\u00d7m\\Delta T_f = K_f \\times m\u0394Tf\u200b=Kf\u200b\u00d7m<\/p>\n\n\n\n<p>Where:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>KfK_fKf\u200b is the freezing point depression constant for benzene.<\/li>\n\n\n\n<li>mmm is the molality of the solution.<\/li>\n<\/ul>\n\n\n\n<p>From the problem:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Kf=5.12\u2009K\u00a0kg\u00a0mol\u22121K_f = 5.12 \\, \\text{K kg mol}^{-1}Kf\u200b=5.12K\u00a0kg\u00a0mol\u22121<\/li>\n\n\n\n<li>m=0.078\u2009mol\/kgm = 0.078 \\, \\text{mol\/kg}m=0.078mol\/kg<\/li>\n<\/ul>\n\n\n\n<p>Substitute the values into the equation:\u0394Tf=5.12\u2009K&nbsp;kg&nbsp;mol\u22121\u00d70.078\u2009mol\/kg\\Delta T_f = 5.12 \\, \\text{K kg mol}^{-1} \\times 0.078 \\, \\text{mol\/kg}\u0394Tf\u200b=5.12K&nbsp;kg&nbsp;mol\u22121\u00d70.078mol\/kg\u0394Tf=0.398\u2009K\\Delta T_f = 0.398 \\, \\text{K}\u0394Tf\u200b=0.398K<\/p>\n\n\n\n<p>So, the freezing point depression is approximately <strong>0.40 K<\/strong> (rounded to two decimal places).<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Explanation:<\/h3>\n\n\n\n<p>The freezing point depression refers to the lowering of the freezing point of a solvent when a solute is added. This phenomenon is dependent on the molality of the solution and the specific properties of the solvent. In this case, benzene\u2019s KfK_fKf\u200b value (5.12 K kg mol\u22121^{-1}\u22121) indicates how much the freezing point will decrease for each mole of solute per kilogram of solvent.<\/p>\n\n\n\n<p>By multiplying the freezing point depression constant KfK_fKf\u200b by the molality of the solution (0.078 mol\/kg), we obtain the freezing point depression. The result tells us how much the freezing point of benzene will decrease when the solute is added.<\/p>\n\n\n\n<p>This depression occurs because the solute particles disrupt the formation of the solvent&#8217;s crystalline structure, requiring a lower temperature to freeze. The freezing point of pure benzene is around 5.5\u00b0C, so after the depression, the new freezing point will be:Tf=5.5\u00b0C\u22120.40\u00b0C=5.10\u00b0CT_f = 5.5\u00b0C &#8211; 0.40\u00b0C = 5.10\u00b0CTf\u200b=5.5\u00b0C\u22120.40\u00b0C=5.10\u00b0C<\/p>\n\n\n\n<p>Thus, the freezing point of the solution is 5.10\u00b0C, and the freezing point depression is 0.40 K.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/07\/learnexams-banner6-692.jpeg\" alt=\"\" class=\"wp-image-257070\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>The freezing point depression constant (Kf) of benzene is 5.12 K kg mol-1. The freezing point depression for the solution of molality 0.078 m containing a non-electrolyte solute in benzene is (rounded off to two decimal places): The Correct Answer and Explanation is: To calculate the freezing point depression (\u0394Tf), we use the formula:\u0394Tf=Kf\u00d7m\\Delta T_f [&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-257069","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/257069","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=257069"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/257069\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=257069"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=257069"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=257069"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}