{"id":225954,"date":"2025-06-04T18:55:51","date_gmt":"2025-06-04T18:55:51","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=225954"},"modified":"2025-06-04T18:55:53","modified_gmt":"2025-06-04T18:55:53","slug":"net-charge-of-citric-acid-at-phs-of","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/04\/net-charge-of-citric-acid-at-phs-of\/","title":{"rendered":"Net charge of citric acid at pHs of"},"content":{"rendered":"\n
Net charge of citric acid at pHs of: 1) 1 2) 5 3) 7 4) 9<\/p>\n\n\n\n
The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n
Net Charge of Citric Acid at Different pH Values<\/strong><\/h3>\n\n\n\n
Citric acid<\/strong> is a triprotic weak acid, meaning it has three carboxylic acid groups<\/strong> (\u2013COOH) and one hydroxyl group<\/strong> (\u2013OH). The three carboxyl groups<\/strong> each have a dissociation constant (pKa<\/strong>) at which they lose a proton:<\/p>\n\n\n\n
These pKa values indicate the pH at which each carboxyl group is 50% dissociated<\/strong>. Using this, we can determine the net charge<\/strong> of citric acid at different pH values by estimating how many protons are lost (deprotonation):<\/p>\n\n\n\n\n\n\n\n
1) pH 1<\/strong><\/h3>\n\n\n\n
\n
pH << pKa\u2081, pKa\u2082, and pKa\u2083<\/li>\n\n\n\n
All three \u2013COOH groups are protonated<\/strong> (neutral)<\/li>\n\n\n\n
The molecule is in its fully protonated form<\/strong><\/li>\n\n\n\n
Net charge = 0<\/strong><\/li>\n<\/ul>\n\n\n\n\n\n\n\n
2) pH 5<\/strong><\/h3>\n\n\n\n
\n
pH > pKa\u2081 and pKa\u2082, but < pKa\u2083<\/li>\n\n\n\n
First and second carboxylic acids are deprotonated<\/strong> (\u2013COO\u207b), third is still protonated<\/strong><\/li>\n\n\n\n
So, two negative charges<\/strong>, one neutral<\/li>\n\n\n\n
Net charge = \u20132<\/strong><\/li>\n<\/ul>\n\n\n\n\n\n\n\n
3) pH 7<\/strong><\/h3>\n\n\n\n
\n
pH > all three pKa values<\/li>\n\n\n\n
All three carboxylic acids are deprotonated<\/strong><\/li>\n\n\n\n
Three negative charges<\/strong><\/li>\n\n\n\n
Net charge = \u20133<\/strong><\/li>\n<\/ul>\n\n\n\n\n\n\n\n
4) pH 9<\/strong><\/h3>\n\n\n\n
\n
pH >> all pKa values<\/li>\n\n\n\n
Same as at pH 7 \u2014 fully deprotonated<\/li>\n\n\n\n
No further ionizable groups<\/li>\n\n\n\n
Net charge = \u20133<\/strong><\/li>\n<\/ul>\n\n\n\n\n\n\n\n
As the pH increases, citric acid loses protons from its acidic groups. This deprotonation is governed by the pKa values of its carboxylic acids. When the pH is well below a group\u2019s pKa, that group remains protonated (neutral). When the pH rises above a group\u2019s pKa, the group tends to lose a proton and becomes negatively charged. This stepwise loss of protons determines the molecule\u2019s net charge at any given <\/p>\n\n\n\n<\/figure>\n","protected":false},"excerpt":{"rendered":"
Net charge of citric acid at pHs of: 1) 1 2) 5 3) 7 4) 9 The Correct Answer and Explanation is: Net Charge of Citric Acid at Different pH Values Citric acid is a triprotic weak acid, meaning it has three carboxylic acid groups (\u2013COOH) and one hydroxyl group (\u2013OH). The three carboxyl groups […]<\/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-225954","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/225954","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=225954"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/225954\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=225954"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=225954"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=225954"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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<\/figure>\n","protected":false},"excerpt":{"rendered":"