What is pH?
pH is a measure of the acidity or basicity of an aqueous solution. It's defined as the negative logarithm of the hydrogen ion concentration:
pH = −log₁₀[H⁺]
pOH = 14 − pH
[H⁺] = 10^(−pH)
pH scale
- pH 0–3: Strongly acidic (battery acid, stomach acid)
- pH 3–6: Weakly acidic (vinegar, orange juice, coffee)
- pH 7: Neutral (pure water)
- pH 8–11: Weakly basic (baking soda, soap)
- pH 11–14: Strongly basic (bleach, drain cleaner)