Question

A buffer contains the weak acid HA and its conjugate base A-. The weak acid has a p Ka of 4.82 and the buffer has a pH of 4.25. This is true of the relative concentration of the weak acid and its conjugate base in the buffer.

a) [HA} > [A-]
b) [Ha} < [A-]
c) [HA]=[A-]

Answer 1

From the henderson-hasslebalch equation: pH=pKa+log[A−]/[HA]

it's apparent that when pKa=pH, c. [HA]=[A^-].