Buffer capacity: resistance, not acid level

The standard

A titrated buffer capacity states how much of a substance is needed to change the pH by a defined amount. The pH value alone says nothing about it.

Criteria

  • It is referred to a defined pH change
  • It distinguishes free and bound acid
  • It is measured, not inferred from the pH value
  • It holds for a given system of acids and salts

Distinction

Buffer capacity ≠ pH value: the pH value is a state, a titrated buffer capacity is its mobility. Buffer capacity ≠ total acidity: two wines of equal total acidity buffer to a different degree.