32 6.4 Strength of Acids and Bases and their Salts

Practice questions

1. Is this statement true? A strong acid completely dissociates (100% ionised) in an aqueous solution, whereas a weak acid does not completely dissociate.
2. Identify each as a strong acid or a weak acid. Assume aqueous solutions.
   1. 1. [latex]\ce{HF}[/latex]
      2. [latex]\ce{HCl}[/latex]
      3. [latex]\ce{H_{2}C_{2}O_{4}}[/latex]
3. Identify each as a strong base or a weak base. Assume aqueous solutions.
   1. 1. [latex]\ce{NaOH}[/latex]
      2. [latex]\ce{Al{(OH)}_{3}}[/latex]
      3. [latex]\ce{C_{4}H_{9}NH_{2}}[/latex]
4. Write a chemical equation for the ionisation of each following acid and indicate whether it proceeds 100% to products or not.
   1. 1. [latex]\ce{HNO_{3}}[/latex]
      2. [latex]\ce{HNO_{2}}[/latex]
      3. [latex]\ce{HI_{3}}[/latex]
5. Identify each salt as neutral, acidic, or basic.
   1. 1. [latex]\ce{NaNO_{2}}[/latex]
      2. [latex]\ce{NaNO_{3}}[/latex]
      3. [latex]\ce{NH_{4}NO_{3}}[/latex]

Answers

1. 1. True
   2. (a) weak acid, (b) strong acid, (c) weak acid
   3. (a) strong base, (b) weak base, (c) weak base
   4. 1. 1. [latex]\ce{HNO_{3}{(aq)}{\rightarrow}H^{+}{(aq)} + NO_{3}^{-}{(aq)}}[/latex] – proceeds 100%
         2. [latex]\ce{HNO_{2}{(aq)}{\rightarrow}H^{+}{(aq)} + NO_{2}^{-}{(aq)}}[/latex] – does not proceed to 100%
         3. [latex]\ce{HI_{3}{(aq)}{\rightarrow}H^{+}{(aq)} + I_{3}^{-}{(aq)}}[/latex] – does not proceed to 100%
   5. 1. basic
      2. neutral
      3. acidic