## Chemistry: Atoms First (2nd Edition)

a. $HCl$ is stronger. b. $HNO_2$ is stronger. c. $HCN$ is stronger.
Using the table 13-2, from page 531, and knowing that: Strong acids: $K_a > 1$ Water: $K_a = 1.0 \times 10^{-14}$ a. $HCl$ is a strong acid: $K_a > 1$ $H_2O$: $K_a = 1.0 \times 10^{-14}$ $HCl$ has the greater $K_a$, so it is the stronger acid. b. $HNO_2$ has $K_a = 4.0 \times 10^{-4}$ $H_2O$ has $K_a = 1.0 \times 10^{-14}$ $HNO_2$ has the greater $K_a$, so it is the stronger acid. c. $HCN$ has $K_a = 6.2 \times 10^{-10}$ $HOC_6H_5$ has $Ka = 1.6 \times 10^{-10}$ $HCN$ has the greater $K_a$, so it is the stronger acid.