According to Henderson – Hasselbalch equation:
pOH = pKb + log ([salt]/ [base])
pKb = – log Kb = – log .85 x 10-5 = 4.733
Therefore, pOH = 4.733 + log (0.2 / 0.1)
= 4.733 + 0.301 = 5.034
pH = 14 – pOH = 14 – 5.034 = 8.966
Calculate the pH of a buffer solution containing 0.2 mole of NH4Cl and 0.1 mole of NH4OH per litre. Kb for NH4OH = 1.85 x 10-5.
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