# Chapter 13 - Exercises - Page 575b: 45

a. $[OH^-] = 1 \times 10^{- 7}M$ : Neutral b. $[OH^-] = 12.05M$ : Basic. c. $[OH^-] = 8.333 \times 10^{- 16}M$ : Acidic. d. $[OH^-] = 1.852 \times 10^{- 10}M$: Acidic.

#### Work Step by Step

$[H_3O^+]$ represents the same thing as $[H^+]$. - If $[H_3O^+] = [OH^-]$: Neutral - If $[H_3O^+] > [OH^-]$: Acidic - If $[H_3O^+] < [OH^-]$: Basic. a. $[H_3O^+] * [OH^-] = Kw = 10^{-14}$ $1 \times 10^{- 7} * [OH^-] = 10^{-14}$ $[OH^-] = \frac{10^{-14}}{ 1 \times 10^{- 7}}$ $[OH^-] = 1 \times 10^{- 7}M$ b. $[H_3O^+] * [OH^-] = Kw = 10^{-14}$ $8.3 \times 10^{- 16} * [OH^-] = 10^{-14}$ $[OH^-] = \frac{10^{-14}}{ 8.3 \times 10^{- 16}}$ $[OH^-] = 12.05$ c. $[H_3O^+] * [OH^-] = Kw = 10^{-14}$ $12 * [OH^-] = 10^{-14}$ $[OH^-] = \frac{10^{-14}}{ 12 \times 10}$ $[OH^-] = 8.333 \times 10^{- 16}$ d. $[H_3O^+] * [OH^-] = Kw = 10^{-14}$ $5.4 \times 10^{- 5} * [OH^-] = 10^{-14}$ $[OH^-] = \frac{10^{-14}}{ 5.4 \times 10^{- 5}}$ $[OH^-] = 1.852 \times 10^{- 10}$

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