Answer:
Henderson Hasselbalch equation: pH = pKa + log [salt]/[acid]
You need to know the pKa for acetic acid. Looking it up one finds it to be 4.76
(a). pH = 4.76 + log [0.13]/[0.10]
= 4.76 + 0.11
= 4.87
(b) KOH + CH3COOH =>H2O + CH3COOK so (acid)goes down and (salt)goes up. Assuming no change in volume, you have 0.10 mol acid - 0.02 mol = 0.08 mol acid and 0.13 mol salt + 0.02 mol = 0.15 mol salt
pH = 4.76 + log [0.15]/[0.08]
= 4.76 + 0.27
= 5.03
