{"id":235931,"date":"2025-06-15T21:15:35","date_gmt":"2025-06-15T21:15:35","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=235931"},"modified":"2025-06-15T21:15:37","modified_gmt":"2025-06-15T21:15:37","slug":"a-solution-of-urea-in-water-has-a-boiling-point-of-100-128-c","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/15\/a-solution-of-urea-in-water-has-a-boiling-point-of-100-128-c\/","title":{"rendered":"A solution of urea in water has a boiling point of 100.128 *C."},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">A solution of urea in water has a boiling point of 100.128 *C. Calculate the freezing point of the same solution: Given Kb and K: for water are 0.512 &#8216;C\/m and 1.86 &#8220;C\/m respectively: Answer: T; =-0.465 %<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>The Correct Answer and Explanation is:<\/strong><sup data-fn=\"2f140373-2c7c-498b-9648-615e3a5080e2\" class=\"fn\"><a id=\"2f140373-2c7c-498b-9648-615e3a5080e2-link\" href=\"#2f140373-2c7c-498b-9648-615e3a5080e2\">1<\/a><\/sup><\/p>\n\n\n\n\n\n<p class=\"wp-block-paragraph\">To determine the freezing point of the urea solution, begin by calculating the molality using the boiling point elevation, then apply that to determine the freezing point depression.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Step 1: Use boiling point elevation to find molality<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Boiling point elevation formula:\u0394Tb=i\u22c5Kb\u22c5m\\Delta T_b = i \\cdot K_b \\cdot m\u0394Tb\u200b=i\u22c5Kb\u200b\u22c5m<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Where:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u0394Tb=Tboiling,solution\u2212Tboiling,pure\u00a0water=100.128\u2218C\u2212100.000\u2218C=0.128\u2218C\\Delta T_b = T_{boiling, solution} &#8211; T_{boiling, pure\\ water} = 100.128^\\circ C &#8211; 100.000^\\circ C = 0.128^\\circ C\u0394Tb\u200b=Tboiling,solution\u200b\u2212Tboiling,pure\u00a0water\u200b=100.128\u2218C\u2212100.000\u2218C=0.128\u2218C<\/li>\n\n\n\n<li>iii is the van&#8217;t Hoff factor for urea, which is 1 (non-electrolyte)<\/li>\n\n\n\n<li>Kb=0.512\u2218C\/mK_b = 0.512^\\circ C\/mKb\u200b=0.512\u2218C\/m<\/li>\n\n\n\n<li>mmm is molality<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Solving for molality mmm:m=\u0394Tbi\u22c5Kb=0.1281\u22c50.512=0.25&nbsp;mol\/kgm = \\frac{\\Delta T_b}{i \\cdot K_b} = \\frac{0.128}{1 \\cdot 0.512} = 0.25\\ \\text{mol\/kg}m=i\u22c5Kb\u200b\u0394Tb\u200b\u200b=1\u22c50.5120.128\u200b=0.25&nbsp;mol\/kg<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Step 2: Use freezing point depression formula<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Freezing point depression formula:\u0394Tf=i\u22c5Kf\u22c5m\\Delta T_f = i \\cdot K_f \\cdot m\u0394Tf\u200b=i\u22c5Kf\u200b\u22c5m<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Where:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Kf=1.86\u2218C\/mK_f = 1.86^\\circ C\/mKf\u200b=1.86\u2218C\/m<\/li>\n\n\n\n<li>i=1i = 1i=1 (urea does not dissociate)<\/li>\n\n\n\n<li>m=0.25\u00a0mol\/kgm = 0.25\\ mol\/kgm=0.25\u00a0mol\/kg<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u0394Tf=1\u22c51.86\u22c50.25=0.465\u2218C\\Delta T_f = 1 \\cdot 1.86 \\cdot 0.25 = 0.465^\\circ C\u0394Tf\u200b=1\u22c51.86\u22c50.25=0.465\u2218C<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Step 3: Calculate the freezing point<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The freezing point of pure water is 0.000\u2218C0.000^\\circ C0.000\u2218C. Since freezing point is depressed:Tf=0.000\u2218C\u22120.465\u2218C=\u22120.465\u2218CT_f = 0.000^\\circ C &#8211; 0.465^\\circ C = -0.465^\\circ CTf\u200b=0.000\u2218C\u22120.465\u2218C=\u22120.465\u2218C<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Conclusion:<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The freezing point of the urea solution is \u22120.465\u2218C-0.465^\\circ C\u22120.465\u2218C.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This outcome demonstrates how a solute such as urea affects the colligative properties of a solvent like water. Despite being a non-electrolyte, urea still lowers the freezing point proportionally to its molality. The calculation involves the use of fundamental relationships between temperature changes and solution concentration, using the known constants KbK_bKb\u200b and KfK_fKf\u200b for water.To determine the freezing point of the urea solution, begin by calculating the molality using the boiling point elevation, then apply that to determine the freezing point depression.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Step 1: Use boiling point elevation to find molality<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Boiling point elevation formula:\u0394Tb=i\u22c5Kb\u22c5m\\Delta T_b = i \\cdot K_b \\cdot m\u0394Tb\u200b=i\u22c5Kb\u200b\u22c5m<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Where:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u0394Tb=Tboiling,solution\u2212Tboiling,pure\u00a0water=100.128\u2218C\u2212100.000\u2218C=0.128\u2218C\\Delta T_b = T_{boiling, solution} &#8211; T_{boiling, pure\\ water} = 100.128^\\circ C &#8211; 100.000^\\circ C = 0.128^\\circ C\u0394Tb\u200b=Tboiling,solution\u200b\u2212Tboiling,pure\u00a0water\u200b=100.128\u2218C\u2212100.000\u2218C=0.128\u2218C<\/li>\n\n\n\n<li>iii is the van&#8217;t Hoff factor for urea, which is 1 (non-electrolyte)<\/li>\n\n\n\n<li>Kb=0.512\u2218C\/mK_b = 0.512^\\circ C\/mKb\u200b=0.512\u2218C\/m<\/li>\n\n\n\n<li>mmm is molality<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Solving for molality mmm:m=\u0394Tbi\u22c5Kb=0.1281\u22c50.512=0.25&nbsp;mol\/kgm = \\frac{\\Delta T_b}{i \\cdot K_b} = \\frac{0.128}{1 \\cdot 0.512} = 0.25\\ \\text{mol\/kg}m=i\u22c5Kb\u200b\u0394Tb\u200b\u200b=1\u22c50.5120.128\u200b=0.25&nbsp;mol\/kg<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Step 2: Use freezing point depression formula<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Freezing point depression formula:\u0394Tf=i\u22c5Kf\u22c5m\\Delta T_f = i \\cdot K_f \\cdot m\u0394Tf\u200b=i\u22c5Kf\u200b\u22c5m<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Where:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Kf=1.86\u2218C\/mK_f = 1.86^\\circ C\/mKf\u200b=1.86\u2218C\/m<\/li>\n\n\n\n<li>i=1i = 1i=1 (urea does not dissociate)<\/li>\n\n\n\n<li>m=0.25\u00a0mol\/kgm = 0.25\\ mol\/kgm=0.25\u00a0mol\/kg<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u0394Tf=1\u22c51.86\u22c50.25=0.465\u2218C\\Delta T_f = 1 \\cdot 1.86 \\cdot 0.25 = 0.465^\\circ C\u0394Tf\u200b=1\u22c51.86\u22c50.25=0.465\u2218C<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Step 3: Calculate the freezing point<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The freezing point of pure water is 0.000\u2218C0.000^\\circ C0.000\u2218C. Since freezing point is depressed:Tf=0.000\u2218C\u22120.465\u2218C=\u22120.465\u2218CT_f = 0.000^\\circ C &#8211; 0.465^\\circ C = -0.465^\\circ CTf\u200b=0.000\u2218C\u22120.465\u2218C=\u22120.465\u2218C<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Conclusion:<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The freezing point of the urea solution is \u22120.465\u2218C-0.465^\\circ C\u22120.465\u2218C.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This outcome demonstrates how a solute such as urea affects the colligative properties of a solvent like water. Despite being a non-electrolyte, urea still lowers the freezing point proportionally to its molality. The calculation involves the use of fundamental relationships between temperature changes and solution concentration, using the known constants KbK_bKb\u200b and KfK_fKf\u200b for water.<\/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-banner10-132.jpeg\" alt=\"\" class=\"wp-image-235932\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>A solution of urea in water has a boiling point of 100.128 *C. Calculate the freezing point of the same solution: Given Kb and K: for water are 0.512 &#8216;C\/m and 1.86 &#8220;C\/m respectively: Answer: T; =-0.465 % The Correct Answer and Explanation is:1 To determine the freezing point of the urea solution, begin by [&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-235931","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/235931","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=235931"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/235931\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=235931"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=235931"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=235931"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}