{"id":3120,"date":"2019-04-22T18:51:33","date_gmt":"2019-04-22T18:51:33","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-introductorychemistry\/chapter\/arrhenius-acids-and-bases-2\/"},"modified":"2019-04-29T12:55:49","modified_gmt":"2019-04-29T12:55:49","slug":"arrhenius-acids-and-bases-2","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-introductorychemistry\/chapter\/arrhenius-acids-and-bases-2\/","title":{"raw":"Arrhenius Acids and Bases","rendered":"Arrhenius Acids and Bases"},"content":{"raw":"
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Learning Objectives<\/h3>\r\n
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  1. Identify an Arrhenius acid and an Arrhenius base.<\/li>\r\n \t
  2. Write the chemical reaction between an Arrhenius acid and an Arrhenius base.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\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>\r\n\r\n

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

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    Example 1<\/h3>\r\n

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

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

      Solution<\/p>\r\n\r\n

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      1. This compound is an ionic compound between H+<\/sup> ions and NO3<\/sub>\u2212<\/sup> ions, so it is an Arrhenius acid.<\/li>\r\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>\r\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>\r\n<\/ol>\r\n

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

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

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

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

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          1. Arrhenius base<\/li>\r\n \t
          2. Arrhenius acid<\/li>\r\n \t
          3. neither<\/li>\r\n<\/ol>\r\n<\/div>\r\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>\r\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>\r\nacid +\u00a0base \u2192\u00a0H2<\/sub>O +\u00a0salt<\/span><\/span>\r\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>\r\n\r\n

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            Example 2<\/h3>\r\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>\r\n

            Solution<\/p>\r\n

            The general reaction is as follows:<\/p>\r\nH2<\/sub>SO4<\/sub> +\u00a0KOH \u2192\u00a0H2<\/sub>O +\u00a0salt<\/span><\/span>\r\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>\r\nH2<\/sub>SO4<\/sub> +\u00a02 KOH \u2192\u00a02 H2<\/sub>O +\u00a0K2<\/sub>SO4<\/sub><\/span><\/span>\r\n

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

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

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

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            Key Takeaways<\/h3>\r\n