Which of the following ionic compounds will yield a solution with a pH < 7 when added to water?

Question

KOH

LiBr

NaF

NaCN

NH₄Cl

Answer 1

NH4Cl will yield a solution with a pH <7. This is because it is the salt of a weak base (NH4OH) and a strong acid (HCl). Thus, hydrolysis of the NH4+ will produce NH3 (weak base) + HCl (strong acid) and pH < 7.

KOH pH >7

LiBr pH = 7

NaF pH >7

NaCN pH >7

NH4Cl pH <7