In the laboratory a general chemistry student measured the p

In the laboratory, a general chemistry student measured the pH of a 0.353 M aqueous solution of ethylamine, C2H5NH2 to be 12.104. Use the information she obtained to determine the Kb for this base. Kb(experiment) =________

Solution

C2H5NH2 is weak base.

PH + POH = 14

POH = 14 - 12.104 = 1.896

we know,

for weak base,

POH = 0.5 * PKb - 0.5 * log C

1.896 = 0.5 * PKb - 0.5 * log (0.353)

PKb = 3.339

-log Kb = 3.339

Kb = 4.57 * 10^-4