A beaker containing 20mL of a 0.200 M solution of methylamine (CH3NH2) is titrated with hydrochloric acid (HCl, 0.200 M). Find the pH when the following quantities of HCl solution have been added.
a) 0 ml
b) 15ml
c) 20ml
For part a I got x=0.00213, part b x=3.03*10^-11 and part c x=2.27*10^-11