## Chemistry: The Molecular Science (5th Edition)

$0.1M$ $H_2S$ is more acidic.
** You can find the $K_a$ values on table: 14.2 (Page 624) Since both solutions have the same concentration, we just have to determine which compound is more acidic: -$H_2S$: $H_2S$ is an acid with $K_a = 1 \times 10^{-7}$ -$HCN$: $HCN$ is an acid with $K_a = 3.3 \times 10^{-10}$ $H_2S$ has a greater $K_a$ value, therefore, it is more acidic. So, $0.1M$ $H_2S$ is more acidic.