## General Chemistry (4th Edition)

Hydronium ion: $[H_3O^+] = 7.1 \times 10^{- 9}M$ Hydroxide ion: $[OH^-] = 1.4 \times 10^{- 6}M$
1. Calculate the hydronium ion concentration. $[H_3O^+] = 10^{-pH}$ $[H_3O^+] = 10^{- 8.15}$ $[H_3O^+] = 7.079 \times 10^{- 9}M$ 2. Use this value to calculate the hydroxide ion concentration: $[H_3O^+] * [OH^-] = Kw = 10^{-14}$ $7.079 \times 10^{- 9} * [OH^-] = 10^{-14}$ $[OH^-] = \frac{10^{-14}}{ 7.079 \times 10^{- 9}}$ $[OH^-] = 1.413 \times 10^{- 6}M$