The next 3 questions will walk you through using the Henderson-Hasselbalch equation for the following question. For each step provide a numerical answer. A solution is made by combining 300mL of 0.020M trimethyl amine, that is (CH3)3N and a 500mL of a 0.03M solution of it's conjugate acid, that is (CH3)3NH . The Kb for trimethyl amine is 6.3x10-5. The Henderson-Hasselbalch equation uses pKa not Kb, Calculate the pKa

The pKa is 13.0.

Explanation:

pKa + pKb = 14

Given, Kb of trimethylamine = 6.3 ×

pKb = - log (6.3 × )

= 1.0

⇒ pKa = 14 - pKb = 14 - 1.0

pKa = 13.0

Check: For most weak acids,  pKa ranges from 2 to 13.

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.