{"id":1564,"date":"2018-03-21T15:27:06","date_gmt":"2018-03-21T15:27:06","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-orgbiochemistry\/chapter\/chemical-properties-of-carboxylic-acids-ionization-and-neutralization\/"},"modified":"2018-11-07T21:36:41","modified_gmt":"2018-11-07T21:36:41","slug":"chemical-properties-of-carboxylic-acids-ionization-and-neutralization","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-monroecc-orgbiochemistry\/chapter\/chemical-properties-of-carboxylic-acids-ionization-and-neutralization\/","title":{"raw":"15.5 Chemical Properties of Carboxylic Acids: Ionization and Neutralization","rendered":"15.5 Chemical Properties of Carboxylic Acids: Ionization and Neutralization"},"content":{"raw":"
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Learning Objectives<\/h3>\r\n
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  1. Name the typical reactions that take place with carboxylic acids.<\/li>\r\n \t
  2. Describe how carboxylic acids react with basic compounds.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

    Water-soluble carboxylic acids are weak acids that ionize slightly in water to form moderately acidic solutions.<\/h3>\r\n RCOOH+H2<\/sub>O\u21c4RCOO\u2212<\/sup>+H3<\/sub>O+ <\/sup><\/span>\r\n

    Their aqueous solutions exhibit the typical properties of acids, such as changing litmus from blue to red.<\/p>\r\n\r\n

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    Note<\/h3>\r\n

    The anion formed when a carboxylic acid dissociates is called the carboxylate<\/em> anion (RCOO\u2212<\/sup>).\u00a0 The specific name of a carboxylate anion comes from the name of the acid.\u00a0 For example, ethanoic acid's anion is ethanoate.\u00a0 Pentanoic acid's anion is pentanoate, and so on.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n

    Whether soluble in water or not, carboxylic acids react with aqueous solutions of sodium hydroxide (NaOH), sodium carbonate (Na2<\/sub>CO3<\/sub>), and sodium bicarbonate (NaHCO3<\/sub>) to form salts:<\/p>\r\nRCOOH + NaOH(aq) \u2192 RCOO\u2212<\/sup>Na+<\/sup>(aq) + H2<\/sub>O<\/span><\/span>\r\n2RCOOH + Na2<\/sub>CO3<\/sub>(aq) \u2192 2RCOO\u2212<\/sup>Na+<\/sup>(aq) + H2<\/sub>O + CO2<\/sub>(g)<\/span><\/span>\r\nRCOOH + NaHCO3<\/sub>(aq) \u2192 RCOO\u2212<\/sup>Na+<\/sup>(aq) + H2<\/sub>O + CO2<\/sub>(g)<\/span><\/span>\r\n

    In these reactions, the carboxylic acids act like inorganic acids: they neutralize basic compounds. With solutions of carbonate (CO3<\/sub>) and bicarbonate (HCO3<\/sub>) ions, they also form carbon dioxide gas.<\/p>\r\n

    Carboxylic acid salts are named in the same manner as inorganic salts: the name of the cation is followed by the name of the organic anion. The name of the anion is obtained by dropping the -ic<\/em> ending of the acid name and replacing it with the suffix -ate<\/em>. This rule applies whether we are using common names or International Union of Pure and Applied Chemistry (IUPAC) names:<\/p>\r\n\r\n

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    Note<\/h3>\r\n

    The salts of long-chain carboxylic acids are called soaps. We discuss the chemistry of soaps further in Chapter 17 \"Lipids\"<\/a>, Section 17.2 \"Fats and Oils\"<\/a>.<\/p>\r\n\r\n

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    Example 3<\/h3>\r\n

    Write an equation for each reaction.<\/p>\r\n\r\n

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    1. the ionization of propanoic acid in water (H2<\/sub>O)<\/li>\r\n \t
    2. the neutralization of propanoic acid with aqueous sodium hydroxide (NaOH)<\/li>\r\n<\/ol>\r\n

      [reveal-answer q=\"213789\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"213789\"]<\/p>\r\n

      1. Propanoic acid has three carbon atoms, so its formula is CH2<\/sub>CH2<\/sub>COOH. Propanoic acid ionizes in water to form a propanoate ion and a hydronium (H3O+) ion.<\/p>\r\n

      CH3<\/sub>CH2<\/sub>COOH(aq) + H2<\/sub>O(\u2113) \u2192 CH3<\/sub>CH2<\/sub>COO\u2212<\/sup>(aq) + H3<\/sub>O+<\/sup>(aq)<\/p>\r\n

      2. Propanoic acid reacts with NaOH(aq) to form sodium propanoate and water.<\/p>\r\n

      CH3<\/sub>CH2<\/sub>COOH(aq) + NaOH(aq) \u2192 CH3<\/sub>CH2<\/sub>COO\u2212<\/sup>Na+<\/sup>(aq) + H2<\/sub>O(\u2113)[\/hidden-answer]<\/p>\r\n\r\n<\/div>\r\n

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      Skill-Building Exercise<\/h3>\r\n

      Write an equation for each reaction.<\/p>\r\n\r\n

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        the ionization of methanoic acid in water<\/p>\r\n\r\n<\/div><\/li>\r\n \t

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        the ionization of 4-chlorobenzoic acid in water<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

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        Example 4<\/h3>\r\n

        Write an equation for the reaction of decanoic acid with each compound.<\/p>\r\n\r\n

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        1. aqueous sodium hydoxide (NaOH)<\/li>\r\n \t
        2. aqueous sodium bicarbonate (NaHCO3<\/sub>)<\/li>\r\n<\/ol>\r\n

          [reveal-answer q=\"80260\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"80260\"]<\/p>\r\n

          1. Decanoic acid has 10 carbon atoms. It reacts with NaOH to form a salt and water (H2<\/sub>O).<\/p>\r\n

          CH3<\/sub>(CH2<\/sub>)8<\/sub>COOH + NaOH(aq) \u2192 CH3<\/sub>(CH2<\/sub>)8<\/sub>COO\u2212<\/sup>Na+<\/sup>(aq) + H2<\/sub>O(\u2113)<\/span><\/span><\/p>\r\n

          2. With NaHCO3<\/sub>, the products are a salt, H2<\/sub>O, and carbon dioxide (CO2<\/sub>).<\/p>\r\n

          CH3<\/sub>(CH2<\/sub>)8<\/sub>COOH + NaHCO3<\/sub>(aq) \u2192 CH3<\/sub>(CH2<\/sub>)8<\/sub>COO\u2212<\/sup>Na+<\/sup>(aq) + H2<\/sub>O(\u2113) + CO2<\/sub>(g)\u00a0<\/span><\/span>[\/hidden-answer]<\/p>\r\n\r\n<\/div>\r\n

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          Skill-Building Exercise<\/h3>\r\n

          Write an equation for the reaction of benzoic acid with each compound.<\/p>\r\n\r\n

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            aqueous sodium hydroxide (NaOH)<\/p>\r\n\r\n<\/div><\/li>\r\n \t

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            aqueous sodium bicarbonate (NaHCO3<\/sub>)<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

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            To Your Health: Organic Salts as Preservatives<\/h3>\r\n

            Some organic salts are used as preservatives in food products. They prevent spoilage by inhibiting the growth of bacteria and fungi. Calcium and sodium propionate, for example, are added to processed cheese and bakery goods; sodium benzoate is added to cider, jellies, pickles, and syrups; and sodium sorbate and potassium sorbate are added to fruit juices, sauerkraut, soft drinks, and wine. Look for them on ingredient labels the next time you shop for groceries.<\/p>\r\n\r\n

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            Concept Review Exercises<\/h3>\r\n
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              How does the neutralization of a carboxylic acid differ from that of an inorganic acid? How are they similar?<\/p>\r\n\r\n<\/div><\/li>\r\n \t

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              What products are formed when a carboxylic acid is neutralized with a strong base? What additional product is formed when a carboxylic acid is neutralized with a carbonate or a bicarbonate compound?<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n

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              [reveal-answer q=\"889280\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"889280\"]<\/p>\r\n\r\n

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              1. Similar: acid + base produces water + a salt.\u00a0 Different: Insoluble carboxylic acids often form soluble carboxylate salts.<\/li>\r\n \t
              2. Both form a carboxylate salt and water; With a carbonate or bicarbonate compound, carbon dioxide is also formed.[\/hidden-answer]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n
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                Key Takeaways<\/h3>\r\n