# Summarizing pH and pOH

## Key Concepts and Summary

The concentration of hydronium ion in a solution of an acid in water is greater than 1.0 $$×$$ 10−7M at 25 °C. The concentration of hydroxide ion in a solution of a base in water is greater than 1.0 $$×$$ 10−7M at 25 °C. The concentration of $${\text{H}}_{3}{\text{O}}^{\text{+}}$$ in a solution can be expressed as the pH of the solution; pH = −log$${\text{H}}_{3}{\text{O}}^{\text{+}}.$$ The concentration of OH can be expressed as the pOH of the solution: pOH = −log[OH]. In pure water, pH = 7.00 and pOH = 7.00

## Key Equations

• $$\text{pH}=\text{−log}\left[{\text{H}}_{3}{\text{O}}^{\text{+}}\right]$$
• pOH = −log[OH]
• [H3O+] = 10−pH
• [OH] = 10−pOH
• pH + pOH = pKw = 14.00 at 25 °C

## Glossary

### acidic

describes a solution in which [H3O+] > [OH]

### basic

describes a solution in which [H3O+] < [OH]

### neutral

describes a solution in which [H3O+] = [OH]

### pH

logarithmic measure of the concentration of hydronium ions in a solution

### pOH

logarithmic measure of the concentration of hydroxide ions in a solution