Question

What must be the molarity of an aqueous solution of
trimethylamine, (CH3)3N, if it has a pH = 11.12?
(CH3) 3N + H2O = (CH3) 3NH+ + OH-
Kb = 6.3 x 10-5​

Answer 1

first find the poh value:

poh=14-ph=14-11.2=2.8

then we apply the following formula:

poh=-lg(√Kb×c)

2.8=-lg(√6.3×10^-5×C)

C((ch3)3n)=0.04М