Question

What will be the pH of 1.0 mol dm-3 of NH4OH, which is 1% dissociated

Answer 1

Reaction is NH4OH <-> NH4+ OH- (note this is reversible)

Draw up an ICE table

Let x be equilibrium conc of OH- assume init conc of OH is 0M and init conc of NH4+ is 0M also. Init conc of NH4OH is 0.1M so equilibrium conc will be 0.1-x.

%dissociation = x/0.1-x * 100%

1 = 100x/0.1-x

0.1-x = 100x

101x = 0.1

x = 0.0009901

pOH = -log(0.0009901) = 3.00