Solution: How do you calculate the pH at the equivalence point for the titration of .190M methylamine with .190M HCl? The Kb of methylamine is 5.0 x 10-4.

Problem

How do you calculate the pH at the equivalence point for the titration of .190M methylamine with .190M HCl? The Kb of methylamine is 5.0 x 10-4.

Solution

We’re being asked to calculate the pH of a solution at equivalence point for the titration of 0.190 M methylamine with 0.190 M HCl. 


HCl (strong acid) will react with CH3NH2 (base).

• CH3NH2 is a base and based on Bronsted-Lowry definition it is a proton acceptor.
• HCl is an acid and based on Bronsted-Lowry definition it is a proton donor.


Reaction:

CH3NH2(aq) + HCl(aq) CH3NH3+(aq) + Cl-(aq)


We will calculate the pH of the solution using the following steps:

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