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. Which statement is true of the relative concentration of the weak acid and its conjugate base in the buffer? a) [HA} [A-] b) [Ha}

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. Which statement 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-]

aaronq · Answer

From the henderson-hasslebalch equation: $\sf pH=pKa+log\dfrac{[A^-]}{[HA]}$

it's apparent that when pKa=pH, [HA]=[A^-].

you should explore the results of the concentrations with the values given (using the equation)