Answer:
7.62
Explanation:
Given that :
pH = 7.8
Conjugate base in solution = 0.6 M
Weak Acid in solution = 0.4 M
Recall :
pH = pKa + log(conjugate base / acid)
Hence,
PKa = pH - log(conjugate base / acid)
pKa = 7.8 - log(0.6 / 0.4)
pKa = 7.8 - log(1.5)
pKa = 7.8 - 0.1760912
pKa = 7.6239088
Hence, pKa = 7.62 (2 decimal places)
