pH buffer: resistance, not value

The standard

A measured buffer capacity names the amount of acid or base that shifts the pH value by one unit, referred to a volume. Without this reference the term states only a direction, not a magnitude.

Criteria

• It refers to a named volume of the solution
• It names the pH range in which it was measured
• It describes a resistance to change, not a state
• It rests on weak acids and their salts

Distinction

pH buffer ≠ pH value: the pH value is a state, the pH buffer the resistance to its change. pH buffer ≠ total acidity: two wines of equal total acidity can buffer differently. Only the measured buffer capacity says how stable a pH value is against intervention.