Question

An aqueous solution contains 0.29 M of benzoic acid (HA) and 0.16 M of sodium benzoate (A-). If the pH of this solution was measured to be 4.63, calculate the pKa of benzoic acid g

Answer 1

pKa = 4.89.

Step-by-step explanation:

We can solve this problem by using the Henderson-Hasselbach equation, which states:

pH = pKa + log
`([A^-])/([HA])`

In this case [A⁻] is the concentration of sodium benzoate and [HA] is the concentration of benzoic acid.

We input the given data:

4.63 = pKa + log
`(0.16)/(0.29)`

And solve for pKa:

pKa = 4.89