Question

The pKa of a weak acid was determined to be 3.39 by measuring the pH of a solution containing the weak acid at 0.20 M and its conjugate base. The measured pH was 3.27. What was the concentration of the conjugate base

Answer 1

0.15 M

Step-by-step explanation:

Hello!

In this case, via the Henderson-Hasselbach equation, we able to write:

`pH=pKa+log(([base])/([acid]) )`

Thus, since we are asked the concentration of the conjugate base ([base]), we proceed as follows:

`3.27=3.39+log(([base])/(0.2M) )\\\\log(([base])/(0.2M) )=-0.12\\\\([base])/(0.2M)=10^(-0.12)`

`[base]=0.2M*0.759`

`[base]=0.15M`

Best regards!