Chapter 16

Predict the direction that predominates in this reaction: $$\mathrm{F}^{-}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{HF}(a q)+\mathrm{OH}^{-}(a q)$$

What does the ionization constant tell us about the strength of an acid?

List the factors on which the \(K_{\mathrm{a}}\) of a weak acid depends.

Why do we normally not quote \(K_{\mathrm{a}}\) values for strong acids such as \(\mathrm{HCl}\) and \(\mathrm{HNO}_{3}\) ? Why is it necessary to specify temperature when giving \(K_{\mathrm{a}}\) values?

Which of the following solutions has the highest \(\mathrm{pH} ?\) (a) \(0.40 \mathrm{M} \mathrm{HCOOH},\) (b) \(0.40 \mathrm{M} \mathrm{HClO}_{4}\) (c) \(0.40 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}\).

Calculate the concentrations of all the species (HCN, \(\mathrm{H}^{+}, \mathrm{CN}^{-},\) and \(\mathrm{OH}^{-}\) ) in a \(0.15 \mathrm{M} \mathrm{HCN}\) solution.

A 0.0560 -g quantity of acetic acid is dissolved in enough water to make \(50.0 \mathrm{~mL}\) of solution. Calculate the concentrations of \(\mathrm{H}^{+}, \mathrm{CH}_{3} \mathrm{COO}^{-},\) and \(\mathrm{CH}_{3} \mathrm{COOH}\) at equilibrium. \(\left(K_{\mathrm{a}}\right.\) for acetic acid \(=\) \(\left.1.8 \times 10^{-5} .\right)\)

The \(\mathrm{pH}\) of an HF solution is 6.20 . Calculate the ratio [conjugate base]/[acid] for HF at this pH.

A \(0.040 M\) solution of a monoprotic acid is 14 percent ionized. Calculate the ionization constant of the acid.

(a) Calculate the percent ionization of a \(0.20 \mathrm{M}\) solution of the monoprotic acetylsalicylic acid (aspirin). \(\left(K_{\mathrm{a}}=3.0 \times 10^{-4} .\right)(\mathrm{b})\) The \(\mathrm{pH}\) of gastric juice in the stomach of a certain individual is 1.00 . After a few aspirin tablets have been swallowed, the concentration of acetylsalicylic acid in the stomach is \(0.20 \mathrm{M}\) Calculate the percent ionization of the acid under these conditions.