What is the Ka for chloroacetic acid (C2H3ClO2) which has a pH of 1.52 in a 0.112 M solution? (4 marks) 1.<\/p>\n\n\n\n
The Correct Answer and Explanation is :<\/strong><\/mark><\/p>\n\n\n\n \ue203To determine the acid dissociation constant (Ka) for chloroacetic acid (C\u2082H\u2083ClO\u2082) in a 0.112 M solution with a pH of 1.52, we can follow these steps:\ue204<\/p>\n\n\n\n 1. Calculate the concentration of hydrogen ions ([H\u207a]):<\/strong><\/p>\n\n\n\n \ue203The pH of a solution is related to the concentration of hydrogen ions by the equation:\ue204\ue206<\/p>\n\n\n\n \ue203pH=\u2212log\u2061[H+]\\text{pH} = -\\log[\\text{H}^+]\ue204\ue206<\/p>\n\n\n\n \ue203Rearranging to solve for [H\u207a]:\ue204\ue206<\/p>\n\n\n\n \ue203[H+]=10\u2212pH[\\text{H}^+] = 10^{-\\text{pH}}\ue204\ue206<\/p>\n\n\n\n \ue203Substituting the given pH value:\ue204\ue206<\/p>\n\n\n\n \ue203[H+]=10\u22121.52\u22480.0302\u2009M[\\text{H}^+] = 10^{-1.52} \\approx 0.0302 \\, \\text{M}\ue204\ue206<\/p>\n\n\n\n 2. Set up the dissociation equilibrium expression:<\/strong><\/p>\n\n\n\n \ue203Chloroacetic acid dissociates in water as follows:\ue204\ue206<\/p>\n\n\n\n \ue203HA\u21ccH++A\u2212\\text{HA} \\rightleftharpoons \\text{H}^+ + \\text{A}^-\ue204\ue206<\/p>\n\n\n\n \ue203The acid dissociation constant (Ka) is given by:\ue204\ue206<\/p>\n\n\n\n \ue203Ka=[H+][A\u2212][HA]K_a = \\frac{[\\text{H}^+][\\text{A}^-]}{[\\text{HA}]}\ue204\ue206<\/p>\n\n\n\n 3. Determine the concentrations at equilibrium:<\/strong><\/p>\n\n\n\n \ue203Let the initial concentration of chloroacetic acid be 0.112 M.\ue204\ue206<\/p>\n\n\n\n \ue203At equilibrium, the concentration of H\u207a ions is 0.0302 M.\ue204\ue206<\/p>\n\n\n\n \ue203Since each mole of HA dissociates to produce one mole of H\u207a and one mole of A\u207b, the concentration of A\u207b at equilibrium is also 0.0302 M.\ue204\ue206<\/p>\n\n\n\n \ue203The concentration of undissociated HA at equilibrium is:\ue204\ue206<\/p>\n\n\n\n \ue203[HA]=0.112\u2009M\u22120.0302\u2009M=0.0818\u2009M[\\text{HA}] = 0.112 \\, \\text{M} – 0.0302 \\, \\text{M} = 0.0818 \\, \\text{M}\ue204\ue206<\/p>\n\n\n\n 4. Calculate Ka:<\/strong><\/p>\n\n\n\n \ue203Substitute the equilibrium concentrations into the Ka expression:\ue204\ue206<\/p>\n\n\n\n \ue203Ka=(0.0302\u2009M)(0.0302\u2009M)0.0818\u2009MK_a = \\frac{(0.0302 \\, \\text{M})(0.0302 \\, \\text{M})}{0.0818 \\, \\text{M}}\ue204\ue206<\/p>\n\n\n\n \ue203Ka\u22480.000912040.0818K_a \\approx \\frac{0.00091204}{0.0818}\ue204\ue206<\/p>\n\n\n\n \ue203Ka\u22481.11\u00d710\u22125K_a \\approx 1.11 \\times 10^{-5}\ue204\ue206<\/p>\n\n\n\n \ue203Therefore, the acid dissociation constant (Ka) for chloroacetic acid in this solution is approximately 1.11 \u00d7 10\u207b\u2075.\ue204<\/p>\n\n\n\n \ue203This calculation demonstrates how the pH of a solution can be used to determine the strength of a weak acid by calculating its Ka.\ue204<\/p>\n","protected":false},"excerpt":{"rendered":" What is the Ka for chloroacetic acid (C2H3ClO2) which has a pH of 1.52 in a 0.112 M solution? (4 marks) 1. The Correct Answer and Explanation is : \ue203To determine the acid dissociation constant (Ka) for chloroacetic acid (C\u2082H\u2083ClO\u2082) in a 0.112 M solution with a pH of 1.52, we can follow these steps:\ue204 […]<\/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-185503","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/185503","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=185503"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/185503\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=185503"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=185503"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=185503"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}