Skip to main content
Chemistry LibreTexts

11.E: Acids and Bases (Exercises)

  • Page ID
    241613
  • Additional Exercises

    1. The properties of a 1.0 M HCl solution and a 1.0 M HC2H3O2 solution are compared. Measurements show that the hydrochloric acid solution has a higher osmotic pressure than the acetic acid solution. Explain why.
    2. Of a 0.50 M HNO3 solution and a 0.50 M HC2H3O2 solution, which should have the higher boiling point? Explain why.
    3. The reaction of sulfuric acid [H2SO4(aq)] with sodium hydroxide [NaOH(aq)] can be represented by two separate steps, with only one hydrogen ion reacting in each step. Write the chemical equation for each step.
    4. The reaction of aluminum hydroxide [Al(OH)3(aq)] with hydrochloric acid [HCl(aq)] can be represented by three separate steps, with only one hydroxide ion reacting in each step. Write the chemical equation for each step.
    5. A friend brings you a small sample of an unknown chemical. Assuming that the chemical is soluble in water, how would you determine if the chemical is an acid or a base?
    6. A neutral solution has a hydrogen ion concentration of about 1 × 10−7 M. What is the concentration of the hydroxide ion in a neutral solution?
    7. The Lewis definitions of an acid and a base are based on electron pairs, not protons. A Lewis acid is an electron pair acceptor, while a Lewis base is an electron pair donor. Use Lewis diagrams to show that

      H+(aq) + OH(aq) → H2O(ℓ)

      is an acid-base reaction in the Lewis sense as well as in the Arrhenius and Brønsted-Lowry senses.

    8. Given the chemical reaction

      NH3(g) + BF3(g) → NH3—BF3(s)

      show that the reaction illustrated by this equation is an acid-base reaction if we use the Lewis definitions of an acid and a base (see Exercise 7). The product contains a bond between the N and B atoms.

    Answers

    1. HCl is a strong acid and yields more ions in solution. HC2H3O2 is a weak acid and undergoes partial ionization in solution.
    2. HNO3 is a strong acid while HC2H3O2 is a weak acid. HNO3 dissociates 100% and its solution contains more ions. The more ions the solution contains the lower is its vapor pressure; the higher temperature is required for it to boil.
    1. H2SO4 + NaOH → NaHSO4 + H2O; NaHSO4 + NaOH → Na2SO4 + H2O
    2. Al(OH)3 + HCl → Al(OH)2Cl + H2O; Al(OH)2Cl + HCl → Al(OH)Cl2 + H2O; Al(OH)Cl2 + HCl → AlCl3 + H2O
    1. One way is to add it to NaHCO3; if it bubbles, it is an acid. Alternatively, add the sample to litmus and look for a characteristic color change (red for acid, blue for base).
    2. In a neutral solution, [OH-] = [H+] = 1.0 x 10-7 M
    1. The O atom is donating an electron pair to the H+ ion, making the base an electron pair donor and the acid an electron pair acceptor.
    2. The N atom is donating a lone pair to B in BF3, Hence NH3 is the Lewis base and BF3 is the Lewis acid.