{"id":218156,"date":"2025-05-23T09:32:47","date_gmt":"2025-05-23T09:32:47","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=218156"},"modified":"2025-05-23T09:32:49","modified_gmt":"2025-05-23T09:32:49","slug":"draw-the-products-of-the-reaction-of-benzoic-acid-with-naoh-aq-and-identify-the-conjugate-acid-and-base-in-the-products","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/05\/23\/draw-the-products-of-the-reaction-of-benzoic-acid-with-naoh-aq-and-identify-the-conjugate-acid-and-base-in-the-products\/","title":{"rendered":"Draw the products of the reaction of benzoic acid with NaOH (aq) and identify the conjugate acid and base in the products"},"content":{"rendered":"\n
Draw the products of the reaction of benzoic acid with NaOH (aq) and identify the conjugate acid and base in the products. Determine the direction of the equilibrium for this reaction and use pKa values to justify your answer. Is the organic product of this reaction water soluble? Why or why not? Using the chemicals provided, benzoic acid, Ethyl p-amino benzoate, Fluor none, Sodium Hydroxide, Hydrochloric Acid, Anhydrous Sodium Sulfate, Diethyl Ether , how might you convert this product back to the original species?<\/p>\n\n\n\n
The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n
Correct Answer Summary:<\/strong><\/h3>\n\n\n\n
Reaction:<\/strong> Benzoic acid (C\u2086H\u2085COOH) reacts with aqueous sodium hydroxide (NaOH) to produce sodium benzoate (C\u2086H\u2085COO\u207b Na\u207a) and water (H\u2082O).<\/p>\n\n\n\n
Conjugate Acid:<\/strong> Water (H\u2082O)<\/li>\n\n\n\n
Conjugate Base:<\/strong> Benzoate ion (C\u2086H\u2085COO\u207b)<\/li>\n<\/ul>\n\n\n\n
Equilibrium Direction:<\/strong><\/p>\n\n\n\n
\n
The reaction favors the products<\/strong>.<\/li>\n\n\n\n
Justification:<\/strong> Benzoic acid has a pKa \u2248 4.2<\/strong>, and water (as a conjugate acid of OH\u207b) has a pKa \u2248 15.7<\/strong>. Equilibrium favors formation of the weaker acid (higher pKa), i.e., water<\/strong>, making the reaction go essentially to completion.<\/li>\n<\/ul>\n\n\n\n
Solubility:<\/strong><\/p>\n\n\n\n
\n
Sodium benzoate<\/strong> is water-soluble<\/strong>.<\/li>\n\n\n\n
Reason:<\/strong> It is an ionic salt<\/strong> formed from a carboxylate anion (C\u2086H\u2085COO\u207b) and sodium cation (Na\u207a), both of which interact well with water molecules via ion-dipole interactions.<\/li>\n<\/ul>\n\n\n\n
Conversion Back to Benzoic Acid:<\/strong><\/p>\n\n\n\n
\n
Add Hydrochloric Acid (HCl)<\/strong> to the sodium benzoate solution.<\/li>\n\n\n\n
The acidic proton from HCl reprotonates the benzoate ion, regenerating benzoic acid.<\/li>\n<\/ul>\n\n\n\n
Isolation:<\/strong><\/p>\n\n\n\n\n
Acidify the aqueous sodium benzoate with HCl to pH ~2.<\/li>\n\n\n\n
Benzoic acid precipitates out (less soluble in water due to loss of ionic character).<\/li>\n\n\n\n
Extract with diethyl ether<\/strong> (benzoic acid is more soluble in ether than in water).<\/li>\n\n\n\n
Dry the organic layer over anhydrous sodium sulfate<\/strong>.<\/li>\n\n\n\n
Evaporate ether to obtain pure benzoic acid.<\/li>\n<\/ol>\n\n\n\n
<\/h3>\n\n\n\n
Benzoic acid is a weak organic acid (C\u2086H\u2085COOH) that reacts with aqueous sodium hydroxide (NaOH), a strong base, in a typical acid-base neutralization reaction. The reaction forms sodium benzoate (C\u2086H\u2085COO\u207b Na\u207a), a salt, and water (H\u2082O). This transformation involves deprotonation of the carboxylic acid group by hydroxide ions.<\/p>\n\n\n\n
In this reaction, benzoic acid (acid) donates a proton to hydroxide (base), forming benzoate ion (C\u2086H\u2085COO\u207b, conjugate base) and water (conjugate acid). The direction of equilibrium is strongly driven toward the formation of products because the base (OH\u207b) is strong, and the resulting conjugate acid (water) is very weak. This is evident from the pKa values: benzoic acid has a pKa of ~4.2, while water\u2019s conjugate acid\/base system has a pKa of 15.7. Since equilibrium favors the formation of the weaker acid (higher pKa), the reaction proceeds nearly to completion toward the products.<\/p>\n\n\n\n
Sodium benzoate is water-soluble due to its ionic nature. The negatively charged carboxylate group interacts favorably with polar water molecules via ion-dipole interactions, enhancing its solubility.<\/p>\n\n\n\n
To regenerate benzoic acid from sodium benzoate, acidification is required. Adding HCl introduces H\u207a ions that protonate the benzoate ion, forming benzoic acid. Since benzoic acid is poorly soluble in water, it precipitates out. Extraction with diethyl ether allows for separation due to benzoic acid\u2019s higher solubility in ether than in water. The ether layer is dried with anhydrous sodium sulfate to remove moisture, then evaporated to yield pure benzoic acid.<\/p>\n\n\n\n
This reversible acid-base chemistry is foundational in organic synthesis and purification strategies.<\/p>\n\n\n\n<\/figure>\n\n\n\n
Draw the products of the reaction of benzoic acid with NaOH (aq) and identify the conjugate acid and base in the products. Determine the direction of the equilibrium for this reaction and use pKa values to justify your answer. Is the organic product of this reaction water soluble? Why or why not? Using the chemicals […]<\/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-218156","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/218156","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=218156"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/218156\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=218156"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=218156"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=218156"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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