Determine [OH−] of a 0.050 M solution of ammonia to which has been added sufficient NH4Cl to make the total [NH=4] equal to 0.100.[Kb(NH3)=1.8×10−5]
pKb⟹Kb=1.8×10−5
pKb=5−log(1.8)=4.745
pOH=pKb+logSaltbase=4.745−log0.1000.050
=4.475−log2
pOH=4.4436
[OH−]=3.6×10−5M