The compound trimethylamine, (CH3)3N, is a weak base when dissolved in water. Write the Kb expression for the weak base equilibrium that occurs in an aqueous solution of trimethylamine: Kb

Kb = [OH⁻] . [C₃H₉NH⁺] / [ C₃H₉N ]

Explanation:

The equation for the reaction of trimethylamine when it is dissolved in water is:

C₃H₉N  +  H₂O ⇄ C₃H₉NH⁺ + OH⁻   Kb

1 mol of trimethylamine catches a proton from the water in order to produce trimethylamonium.

It is a base, because it give OH⁻ to the medium

Expression for Kb (Molar concentration)

Kb = [OH⁻] . [C₃H₉NH⁺] / [ C₃H₉N ]