Answer:
4.16
Explanation:
Considering the Henderson- Hasselbalch equation for the calculation of the pH of the buffer solution as:
pH=pKa+log[base]/[acid]
Where Ka is the dissociation constant of the acid.
Given that:
pKa = 3.86
Given, concentration of acid = [acid] = 0.4 M
concentration of base = [base] = 0.8 M
So,
pH=3.86+log(0.8/0.4) = 4.16
