ChemAtlas

Chapter 10

Acids and bases

pH is a logarithm, so every whole step is a factor of ten in hydrogen ion concentration.

01234567891011121314AcidicNeutralBasicStomach acidVinegarCoffeePure waterBloodBaking sodaAmmoniaBleachpH = −log[H⁺]pH + pOH = 14[H⁺][OH⁻] = 1.0 × 10⁻¹⁴
Fig. 5Each whole step is a tenfold change in hydrogen ion concentration. Blood holds between 7.35 and 7.45 — a tenth of a unit outside that range is a medical emergency.
Start from
024678101214

pH

3

acidic

pOH

11

[H⁺]

1.000e-3M

[OH⁻]

1.000e-11M

Working

  1. 01Starting from pH = 3
  2. 02[H⁺] = 10^(−pH) = 10^(−3)1.000e-3 M
  3. 03[OH⁻] = Kw ÷ [H⁺] = 1.0 × 10⁻¹⁴ ÷ 1.000e-31.000e-11 M

For scale

SubstancepH
Battery acid0.5
Stomach acid1.5
Lemon juice2.4
Vinegar2.9
Tomato juice4.2
Black coffee5
Urine6
Pure water7
Blood7.4
Seawater8.1
Baking soda8.4
Milk of magnesia10.5
Ammonia11.6
Bleach12.6
Drain cleaner14