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pH, pOH & Acid-Base Calculator

Enter any one of pH, pOH, hydrogen ion concentration, or hydroxide ion concentration, and this tool computes the other three instantly. A color-coded pH scale shows where your solution falls.

pH Scale

012345678910111213147.0AcidicNeutralBasic

Input

Results

Classification
Neutral
pH
7.0000
pOH
7.0000
[H⁺]
1.000 × 10^-7 M
[OH⁻]
1.000 × 10^-7 M

Step-by-Step Calculation

1. Given pH

pH=7.0000\text{pH} = 7.0000

2. Calculate pOH

pOH=14−pH=14−7.0000=7.0000\text{pOH} = 14 - \text{pH} = 14 - 7.0000 = 7.0000

3. Calculate [H⁺]

[H+]=10−pH=10−7.0000=1.000×10−7 M[\text{H}^+] = 10^{-\text{pH}} = 10^{-7.0000} = 1.000 \times 10^{-7} \text{ M}

4. Calculate [OH⁻]

[OH−]=10−pOH=10−7.0000=1.000×10−7 M[\text{OH}^-] = 10^{-\text{pOH}} = 10^{-7.0000} = 1.000 \times 10^{-7} \text{ M}

5. Verify relationship

[H+]×[OH−]=1.000×10−14≈10−14[\text{H}^+] \times [\text{OH}^-] = 1.000 \times 10^{-14} \approx 10^{-14}

Reference Guide

pH and pOH

pH measures how acidic or basic a solution is on a scale from 0 to 14. pH and pOH always sum to 14 in water at 25 degrees C.

pH+pOH=14\text{pH} + \text{pOH} = 14

Ion Concentrations

pH is the negative logarithm of the hydrogen ion concentration. The product of hydrogen and hydroxide concentrations is always 10 to the minus 14.

[H+][OH−]=10−14[\text{H}^+][\text{OH}^-] = 10^{-14}

The pH Scale

Values below 7 are acidic, 7 is neutral, and above 7 are basic. Each whole number change represents a tenfold change in hydrogen ion concentration.

Common pH Values

Battery acid is around pH 1, lemon juice pH 2, coffee pH 5, blood pH 7.4, baking soda pH 8.3, ammonia pH 11, and bleach pH 12.5.