{"id":603,"date":"2017-12-14T21:42:06","date_gmt":"2017-12-14T21:42:06","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/chapter\/arrhenius-acids-and-bases\/"},"modified":"2017-12-14T21:42:06","modified_gmt":"2017-12-14T21:42:06","slug":"arrhenius-acids-and-bases","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-introductory-chemistry\/chapter\/arrhenius-acids-and-bases\/","title":{"raw":"Arrhenius Acids and Bases","rendered":"Arrhenius Acids and Bases"},"content":{"raw":"
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Learning Objectives<\/h3>\n
  1. Identify an Arrhenius acid and an Arrhenius base.<\/li>\n\t
  2. Write the chemical reaction between an Arrhenius acid and an Arrhenius base.<\/li>\n<\/ol><\/div>\n<\/div>\n

    Historically, the first chemical definition of an acid and a base was put forward by Svante Arrhenius, a Swedish chemist, in 1884. An Arrhenius acid<\/a><\/span>\u00a0is a compound that increases the H+<\/sup> ion concentration in aqueous solution. The H+<\/sup> ion is just a bare proton, and it is rather clear that bare protons are not floating around in an aqueous solution. Instead, chemistry has defined the hydronium ion<\/a><\/span>\u00a0(H3<\/sub>O+<\/sup>) as the actual chemical species that represents an H+<\/sup> ion. H+<\/sup> ions and H3<\/sub>O+<\/sup> ions are often considered interchangeable when writing chemical equations (although a properly balanced chemical equation should also include the additional H2<\/sub>O). Classic Arrhenius acids can be considered ionic compounds in which H+<\/sup> is the cation. Table 12.1 \"Some Arrhenius Acids\"<\/a> lists some Arrhenius acids and their names.<\/p>\n\n

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    Table 12.1<\/span> Some Arrhenius Acids<\/p>\n\n
    Formula<\/th>\nName<\/th>\n<\/tr><\/thead>
    HC2<\/sub>H3<\/sub>O2<\/sub> (also written CH3<\/sub>COOH)<\/td>\nacetic acid<\/td>\n<\/tr>
    HClO3<\/sub><\/td>\nchloric acid<\/td>\n<\/tr>
    HCl<\/td>\nhydrochloric acid<\/td>\n<\/tr>
    HBr<\/td>\nhydrobromic acid<\/td>\n<\/tr>
    HI<\/td>\nhydriodic acid<\/td>\n<\/tr>
    HF<\/td>\nhydrofluoric acid<\/td>\n<\/tr>
    HNO3<\/sub><\/td>\nnitric acid<\/td>\n<\/tr>
    H2<\/sub>C2<\/sub>O4<\/sub><\/td>\noxalic acid<\/td>\n<\/tr>
    HClO4<\/sub><\/td>\nperchloric acid<\/td>\n<\/tr>
    H3<\/sub>PO4<\/sub><\/td>\nphosphoric acid<\/td>\n<\/tr>
    H2<\/sub>SO4<\/sub><\/td>\nsulfuric acid<\/td>\n<\/tr>
    H2<\/sub>SO3<\/sub><\/td>\nsulfurous acid<\/td>\n<\/tr><\/tbody><\/table><\/div>\n

    An Arrhenius base<\/a><\/span>\u00a0is a compound that increases the OH\u2212<\/sup> ion concentration in aqueous solution. Ionic compounds of the OH\u2212<\/sup> ion are classic Arrhenius bases.<\/p>\n\n

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    Example 1<\/h3>\n

    Identify each compound as an Arrhenius acid, an Arrhenius base, or neither.<\/p>\n\n

    1. HNO3<\/sub><\/li>\n\t
    2. CH3<\/sub>OH<\/li>\n\t
    3. Mg(OH)2<\/sub><\/li>\n<\/ol>

      Solution<\/p>\n\n

      1. This compound is an ionic compound between H+<\/sup> ions and NO3<\/sub>\u2212<\/sup> ions, so it is an Arrhenius acid.<\/li>\n\t
      2. Although this formula has an OH in it, we do not recognize the remaining part of the molecule as a cation. It is neither an acid nor a base. (In fact, it is the formula for methanol, an organic compound.)<\/li>\n\t
      3. This formula also has an OH in it, but this time we recognize that the magnesium is present as Mg2+<\/sup> cations. As such, this is an ionic compound of the OH\u2212<\/sup> ion and is an Arrhenius base.<\/li>\n<\/ol>

        Test Yourself<\/em><\/p>\n

        Identify each compound as an Arrhenius acid, an Arrhenius base, or neither.<\/p>\n\n

        1. KOH<\/li>\n\t
        2. H2<\/sub>SO4<\/sub><\/li>\n\t
        3. C2<\/sub>H6<\/sub><\/li>\n<\/ol>

          Answer<\/em><\/p>\n\n

          1. Arrhenius base<\/li>\n\t
          2. Arrhenius acid<\/li>\n\t
          3. neither<\/li>\n<\/ol><\/div>\n

            Acids have some properties in common. They turn litmus, a plant extract, red. They react with some metals to give off H2<\/sub> gas. They react with carbonate and hydrogen carbonate salts to give off CO2<\/sub> gas. Acids that are ingested typically have a sour, sharp taste. (The name acid<\/em> comes from the Latin word acidus<\/em>, meaning \u201csour.\u201d) Bases also have some properties in common. They are slippery to the touch, turn litmus blue, and have a bitter flavour if ingested.<\/p>\n

            Acids and bases have another property: they react with each other to make water and an ionic compound called a salt. A salt<\/a><\/span>, in chemistry, is any ionic compound made by combining an acid with a base. A reaction between an acid and a base is called a neutralization reaction<\/a><\/span>\u00a0and can be represented as follows:<\/p>\nacid +\u00a0base \u2192\u00a0H2<\/sub>O +\u00a0salt<\/span><\/span>\n

            The stoichiometry of the balanced chemical equation depends on the number of H+<\/sup> ions in the acid and the number of OH\u2212<\/sup> ions in the base.<\/p>\n\n

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            Example 2<\/h3>\n

            Write the balanced chemical equation for the neutralization reaction between H2<\/sub>SO4<\/sub> and KOH. What is the name of the salt that is formed?<\/p>\n

            Solution<\/p>\n

            The general reaction is as follows:<\/p>\nH2<\/sub>SO4<\/sub> +\u00a0KOH \u2192\u00a0H2<\/sub>O +\u00a0salt<\/span><\/span>\n

            Because the acid has two H+<\/sup> ions in its formula, we need two OH\u2212<\/sup> ions to react with it, making two H2<\/sub>O molecules as product. The remaining ions, K+<\/sup> and SO4<\/sub>2\u2212<\/sup>, make the salt potassium sulfate (K2<\/sub>SO4<\/sub>). The balanced chemical reaction is as follows:<\/p>\nH2<\/sub>SO4<\/sub> +\u00a02 KOH \u2192\u00a02 H2<\/sub>O +\u00a0K2<\/sub>SO4<\/sub><\/span><\/span>\n

            Test Yourself<\/em><\/p>\n

            Write the balanced chemical equation for the neutralization reaction between HCl and Mg(OH)2<\/sub>. What is the name of the salt that is formed?<\/p>\n

            Answer<\/em><\/p>\n

            2 HCl +\u00a0Mg(OH)2<\/sub> \u2192\u00a02 H2<\/sub>O +\u00a0MgCl2<\/sub>; magnesium chloride<\/p>\n\n<\/div>\n

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            Key Takeaways<\/h3>\n