{"id":230928,"date":"2025-06-10T08:27:08","date_gmt":"2025-06-10T08:27:08","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=230928"},"modified":"2025-06-10T08:27:11","modified_gmt":"2025-06-10T08:27:11","slug":"what-is-the-conjugate-base-of-each-of-the-following-acids","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/10\/what-is-the-conjugate-base-of-each-of-the-following-acids\/","title":{"rendered":"What is the conjugate base of each of the following acids"},"content":{"rendered":"\n

What is the conjugate base of each of the following acids? (do not include a counterion) ???? OH (a) (b) OH 4. What is the conjugate acid of each of the following bases? (do not include a counterion) (a) H (b) OH 5. Use the following reaction to answer each part of this question: NaCN + OH HCN + JoNa (a) Label the acid, base, conjugate acid, and conjugate base. (b) What is the pka of the acid and of the conjugate acid? (c) What is the strongest acid in this reaction? (d) Does the equilibrium lie to the left (toward reactants) or to the right (toward products)?<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

3. What is the conjugate base of each of the following acids?<\/strong><\/h3>\n\n\n\n

(a) ![Structure] A carboxylic acid (likely phenylacetic acid):<\/p>\n\n\n\n

    \n
  • Answer:<\/strong> The conjugate base is the carboxylate anion: Ph-CH2-COO\u2212\\text{Ph-CH}_2\\text{-COO}^-Ph-CH2\u200b-COO\u2212 (Deprotonation of the \u2013COOH group)<\/li>\n<\/ul>\n\n\n\n

    (b) Ethanol (CH\u2083CH\u2082OH):<\/p>\n\n\n\n

      \n
    • Answer:<\/strong> The conjugate base is the ethoxide ion: CH3CH2O\u2212\\text{CH}_3\\text{CH}_2\\text{O}^-CH3\u200bCH2\u200bO\u2212<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n

      4. What is the conjugate acid of each of the following bases?<\/strong><\/h3>\n\n\n\n

      (a) H\u207b (hydride):<\/p>\n\n\n\n

        \n
      • Answer:<\/strong> The conjugate acid is H\u2082 (hydrogen gas): H\u2212+H+\u2192H2\\text{H}^- + \\text{H}^+ \\rightarrow \\text{H}_2H\u2212+H+\u2192H2\u200b<\/li>\n<\/ul>\n\n\n\n

        (b) CH\u2083CH\u2082O\u207b (ethoxide ion):<\/p>\n\n\n\n

          \n
        • Answer:<\/strong> The conjugate acid is ethanol (CH\u2083CH\u2082OH)<\/li>\n<\/ul>\n\n\n\n
          \n\n\n\n

          5. Reaction:<\/strong><\/h3>\n\n\n\n

          NaCN+CH3CH2COOH\u21ccHCN+CH3CH2COO\u2212\\text{NaCN} + \\text{CH}_3\\text{CH}_2\\text{COOH} \\rightleftharpoons \\text{HCN} + \\text{CH}_3\\text{CH}_2\\text{COO}^-NaCN+CH3\u200bCH2\u200bCOOH\u21ccHCN+CH3\u200bCH2\u200bCOO\u2212<\/p>\n\n\n\n

          (a) Label each:<\/strong><\/p>\n\n\n\n

            \n
          • Acid: CH\u2083CH\u2082COOH (propionic acid)<\/li>\n\n\n\n
          • Base: CN\u207b (from NaCN)<\/li>\n\n\n\n
          • Conjugate acid: HCN<\/li>\n\n\n\n
          • Conjugate base: CH\u2083CH\u2082COO\u207b<\/li>\n<\/ul>\n\n\n\n

            (b) pKa values:<\/strong><\/p>\n\n\n\n

              \n
            • CH\u2083CH\u2082COOH (propionic acid): ~4.9<\/li>\n\n\n\n
            • HCN: ~9.2<\/li>\n<\/ul>\n\n\n\n

              (c) Strongest acid:<\/strong><\/p>\n\n\n\n

                \n
              • CH\u2083CH\u2082COOH (lower pKa = stronger acid)<\/li>\n<\/ul>\n\n\n\n

                (d) Equilibrium direction:<\/strong><\/p>\n\n\n\n

                  \n
                • Equilibrium favors the formation of the weaker acid and base<\/strong>.<\/li>\n\n\n\n
                • Since CH\u2083CH\u2082COOH is a stronger acid than HCN, the reaction favors the right<\/strong> (products).<\/li>\n<\/ul>\n\n\n\n
                  \n\n\n\n

                  Explanation <\/strong><\/h3>\n\n\n\n

                  In acid-base chemistry, every acid has a conjugate base, formed by removing a proton (H\u207a), and every base has a conjugate acid, formed by adding a proton. For instance, phenylacetic acid loses H\u207a to form its carboxylate conjugate base, while ethanol forms ethoxide ion when deprotonated.<\/p>\n\n\n\n

                  Conversely, hydride (H\u207b) accepts a proton to form diatomic hydrogen gas (H\u2082), and the ethoxide ion gains a proton to regenerate ethanol, showing the reversibility of acid-base reactions.<\/p>\n\n\n\n

                  In the reaction between NaCN and propionic acid (CH\u2083CH\u2082COOH), we identify propionic acid as the acid (donates H\u207a) and cyanide ion (CN\u207b) as the base (accepts H\u207a). Their conjugate counterparts are HCN (from CN\u207b) and propionate (CH\u2083CH\u2082COO\u207b, from the acid).<\/p>\n\n\n\n

                  The strength of acids is compared using their pKa values. A lower pKa indicates a stronger acid. Here, propionic acid has a pKa of ~4.9, while HCN has a pKa of ~9.2, meaning propionic acid is stronger. Since reactions typically favor the formation of the weaker acid and base (equilibrium principle), the reaction shifts toward the right side \u2014 favoring HCN and the propionate ion.<\/p>\n\n\n\n

                  This understanding is foundational in predicting acid-base reaction direction, strength comparisons, and ion stability \u2014 key skills in general and organic chemistry.<\/p>\n\n\n\n

                  \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

                  What is the conjugate base of each of the following acids? (do not include a counterion) ???? OH (a) (b) OH 4. What is the conjugate acid of each of the following bases? (do not include a counterion) (a) H (b) OH 5. Use the following reaction to answer each part of this question: NaCN […]<\/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-230928","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/230928","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=230928"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/230928\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=230928"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=230928"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=230928"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}