29 6.1 Definitions and Theories of Acids and Bases

Practice questions

1. 1. 1. 1. 1. Identify each substance as an Arrhenius acid, an Arrhenius base, or neither.
               1. 1. [latex]\ce{NaOH}[/latex]
                  2. [latex]\ce{C_{2}H_{5}OH}[/latex]
                  3. [latex]\ce{H_{3}PO_{4}}[/latex]
                  4. [latex]\ce{Ba{(OH)}_{2}}[/latex]
                  5. [latex]\ce{HNO_{2}}[/latex]
                  6. [latex]\ce{C_{6}H_{12}O_{6}}[/latex]
            2. What is the balanced chemical equation for the neutralisation reaction between [latex]\ce{KOH}[/latex] and [latex]\ce{H_{2}C_{2}O_{4}}[/latex]?
               1. 1. [latex]\ce{KOH + H_{2}C_{2}O_{4} {\rightarrow} 2H_{2}O + K_{2}C_{2}O_{4}}[/latex]
                  2. [latex]\ce{2KOH + H_{2}C_{2}O_{4} {\rightarrow} K_{2}C_{2}O_{4}}[/latex]
                  3. [latex]\ce{2KOH + H_{2}C_{2}O_{4} {\rightarrow} 2H_{2}O + H_{2}C_{2}O_{4}}[/latex]
                  4. [latex]\ce{2KOH + H_{2}C_{2}O_{4} {\rightarrow} 2H_{2}O + K_{2}C_{2}O_{4}}[/latex]
            3. Is the following statement true? The balanced chemical equation for the neutralisation reaction between [latex]\ce{HCl}[/latex] and [latex]\ce{Fe{(OH)}_{3}}[/latex] is [latex]\ce{3HCl + Fe{(OH)}_{3} {\rightarrow} 3H_{2}O + FeCl_{3}}[/latex].
            4. How does Brønsted-Lowry acid differ from an Arrhenius acid?
               1. 1. A Brønsted-Lowry acid is a proton donor. It decreases the [latex]\ce{H^{+}}[/latex] concentration in water.
                  2. A Brønsted-Lowry acid is a proton donor. It increases the [latex]\ce{OH^{-}}[/latex] concentration in water.
                  3. A Brønsted-Lowry acid is a proton donor. It does not necessarily increase the [latex]\ce{H^{+}}[/latex] concentration in water.
                  4. A Brønsted-Lowry acid is a proton donor. It increases the [latex]\ce{H^{+}}[/latex] in water.
            5. The following equation shows the dissociation of hydrogen bromide in water as a Brønsted-Lowry acid-base reaction. Identify the proton donor and proton acceptor in this reaction: [latex]\ce{HBr + H_{2}O {\rightarrow} H_{3}O^{+} + Br^{-}}[/latex].
            6. Pyridine ([latex]\ce{C_{5}H_{5}N}[/latex]) acts as a Brønsted-Lowry base in water. The hydrolysis reaction for pyridine is shown below. Identify the Brønsted-Lowry acid and Brønsted-Lowry base in this reaction: [latex]\ce{C_{5}H_{5}N + H_{2}O {\rightarrow} C_{5}H_{5}NH^{+} + OH^{-}}[/latex].
            7. Identify the Brønsted-Lowry acid and Brønsted-Lowry base in this chemical equation: [latex]\ce{H_{3}PO_{4} + OH^{-} {\rightarrow} H_{2}PO_{4}^{-} + H_{2}O}[/latex].
            8. Predict the products of this reaction, assuming it undergoes a Brønsted-Lowry acid-base reaction: [latex]\ce{HC_{2}H_{3}O_{2} + C_{5}H_{5}N {\rightarrow} ?}[/latex]
               1. 1. [latex]\ce{C_{2}H_{3}O_{2}^{-}}[/latex] and [latex]\ce{C_{5}H_{5}NH^{+}}[/latex]
                  2. [latex]\ce{C_{2}H_{3}O_{2}^{+}}[/latex] and [latex]\ce{C_{5}H_{5}NH^{-}}[/latex]
                  3. [latex]\ce{H_{2}O}[/latex] and [latex]\ce{C_{5}H_{5}NH^{+}}[/latex]
                  4. [latex]\ce{C_{2}H_{3}O_{2}^{-}}[/latex] and [latex]\ce{H_{2}O}[/latex]
            9. What is the conjugate acid of: (A) [latex]\ce{H_{2}O}[/latex] and (B) [latex]\ce{NH_{3}}[/latex]?
               1. 1. A= [latex]\ce{H_{3}O^{+}}[/latex], B= [latex]\ce{NH_{4}^{+}}[/latex]
                  2. A= [latex]\ce{CH_{3}OH}[/latex] , B= [latex]\ce{N_{2}}[/latex]
                  3. A= [latex]\ce{H_{2}O^{+}}[/latex], B= [latex]\ce{NH_{3}^{+}}[/latex]
                  4. A= [latex]\ce{OH^{-}}[/latex], B= [latex]\ce{NH_{2}^{-}}[/latex]
            10. What is the conjugate base of: (A) [latex]\ce{HSO_{4}^{-}}[/latex] and (B) [latex]\ce{H_{2}O}[/latex]?
                1. 1. A= [latex]\ce{S}[/latex] , B= [latex]\ce{H^{+}}[/latex]
                   2. A= [latex]\ce{SO_{4}^{2-}}[/latex] , B= [latex]\ce{H^{+}}[/latex]
                   3. A= [latex]\ce{HSO_{4}^{2-}}[/latex] , B= [latex]\ce{OH^{-}}[/latex]
                   4. A= [latex]\ce{SO_{4}^{2-}}[/latex] , B= [latex]\ce{OH^{-}}[/latex]
            11. Identify the conjugate acid-base pairs in this reaction: [latex]\ce{HSO_{4}^{-} + PO_{4}^{3-} {\rightarrow} SO_{4}^{2-} + HPO_{4}^{2-}}[/latex].
                1. 1. [latex]\ce{HSO_{4}^{-}}[/latex] and [latex]\ce{SO_{4}^{2-}}[/latex];  [latex]\ce{PO_{4}^{3-}}[/latex] and [latex]\ce{HPO_{4}^{2-}}[/latex].
                   2. [latex]\ce{HSO_{4}^{-}}[/latex] and [latex]\ce{PO_{4}^{3-}}[/latex];  [latex]\ce{SO_{4}^{2-}}[/latex] and [latex]\ce{HPO_{4}^{2-}}[/latex].
                   3. [latex]\ce{HSO_{4}^{-}}[/latex] and [latex]\ce{HPO_{4}^{2-}}[/latex];  [latex]\ce{SO_{4}^{2-}}[/latex] and [latex]\ce{PO_{4}^{3-}}[/latex].
                   4. None of the above
            12. Identify the conjugate acid-base pairs in this reaction: [latex]\ce{NH_{3}^{+} + C_{6}H_{5}O^{-} {\rightarrow} C_{6}H_{5}OH + NH_{2}^{-}}[/latex].
                1. 1. [latex]\ce{NH_{3}}[/latex] and [latex]\ce{NH_{2}^{-}}[/latex]; [latex]\ce{C_{6}H_{5}O^{-}}[/latex] and [latex]\ce{C_{6}H_{5}OH}[/latex]
                   2. [latex]\ce{NH_{3}}[/latex] and [latex]\ce{C_{6}H_{5}O^{-}}[/latex]; [latex]\ce{C_{6}H_{5}OH}[/latex] and [latex]\ce{NH_{2}^{-}}[/latex]
                   3. [latex]\ce{NH_{3}}[/latex] and [latex]\ce{C_{6}H_{5}OH}[/latex]; [latex]\ce{NH_{2}^{-}}[/latex] and [latex]\ce{C_{6}H_{5}OH^{-}}[/latex]
                   4. None of the above

Answers

1. 1. (a) and (d) are Arrhenius bases, (c) and (e) are Arrhenius acids, (b) and (f) are neither
   2. d
   3. True
   4. c
   5. [latex]\ce{HBr}[/latex] – proton donor, [latex]\ce{H_{2}O}[/latex] – proton acceptor
   6. [latex]\ce{H_{2}O}[/latex] – Brønsted-Lowry acid ,  [latex]\ce{C_{5}H_{5}N}[/latex] – Brønsted-Lowry base
   7. [latex]\ce{H_{3}PO_{4}}[/latex] – Brønsted-Lowry acid, [latex]\ce{OH^{-}}[/latex] – Brønsted-Lowry base
   8. a
   9. a
   10. d
   11. a
   12. a