Page 41 - Analytical Chemistry I E-book
P. 41
pH of Salts
1- Salt of strong acid and strong base:
Those derived from strong acids and bases e.g., potassium
chloride. (KCl) Solution of such salts is neutral in reaction(pH 7).
2- Salt of strong acid and weak base:
Those derived from strong acids and weak bases e.g., ammonium
chloride (NH4Cl) Solution of such salts is acidic (pH<7).
pH= 7- ½ pKb + ½ PCs
Where Cs is the molar concentration of the salt.
EX: Calculate pH of 0.01M NH4Cl, pKb = 8.62
NH4Cl is a salt of weak base and a strong acid, Cs = 0.01.
So that pH = 7 - ½ (8.62) + ½ (-Log 0.01) = 3.69.
