Question

Acetic acid is a weak acid with a pKa of 4.76. What is the concentration of acetate in a buffer solution of 0.2M at pH 4.9. Give your answer in M but as a numeral only to 2 decimal places.

Answer 1

`[base]=0.28M`

Step-by-step explanation:

Hello,

In this case, by using the Henderson-Hasselbach equation one can compute the concentration of acetate, which acts as the base, as shown below:

`pH=pKa+log(([base])/([acid]) )\\\\([base])/([acid])=10^(pH-pKa)\\\\([base])/([acid])=10^(4.9-4.76)\\\\([base])/([acid])=1.38\\\\`

`[base]=1.38[acid]=1.38*0.20M=0.28M`

Regards.