## Chemistry 12th Edition

(a) 1. Find the concentration of $[OH^-]$ $Ba(OH)_2$ is a strong base, and has 2 $OH$, therefore, the concentration of $OH^-$ will be the double of the base concentration. $[OH^-] = [Ba(OH)_2] * 2 = 2.8 \times 10^{-4} * 2 = 5.6 \times 10^{-4}M$ 2. Calculate the pOH and then the pH. $pOH = -log[OH^-] = -log(5.6 \times 10^{-4}) = 3.25$ $pOH + pH = 14$ $3.25 + pH = 14$ $pH = 14 - 3.25 = 10.75$ (b) 1. Find the concentration of $[H^+]$: $HNO_3$ is a strong acid. $[HNO_3] = [H^+] = 5.2 \times 10^{-4}M$ 2. Calculate the pH. $pH = -log[H^+] = -log(5.2 \times 10^{-4}) = 3.28$