Question

Buffer capacity of a buffer is given as two units for a change in pH by Unity. Then what is the number of moles of acid or base, added in one litre of the solution?

(a) 2

(b) 0.5

(c) 1

(d) 4

I had been asked this question in an international level competition.

I'm obligated to ask this question of Equilibrium topic in chapter Equilibrium of Chemistry – Class 11

Answer 1

Right choice is (a) 2

The explanation: Buffer capacity is denoted by Φ = number of moles of acid or base added to one litre of the buffer by a change in pH. Here the change in pH is given by 1 and the buffer capacity is given by 2, therefore by substituting, we get that 2 moles of acid or base are added in one litre of the solution.