Dimethylamine, (CH3)2NH, is an organic base with pKb= 3.23at 298K. In an experiment, a 40.0 mL sample of 0.105mol/L-1(CH3)2NH(aq)istitrated with 0.150mol/L-11HI(aq)at 298 K.
(a) Write a balanced chemical equation for the neutralizationreaction upon which this titration is based, and indicate clearlywhich atom is being protonated. Then, calculate the equilibriumconstant for the neutralization reaction. (Hint: To calculate theequilibrium constant, you may find it helpful to represent theneutralization reaction as the sum of twoor morereactions.)
(b) Calculate the pH, [(CH3)2NH], and[(CH3)2NH2+] at thefollowing stages of the titration. Justify any approximations.
i) before the addition of any HI solution
ii) after the addition of 20.0 mL of HI solution
iii) at the equivalence point
iv) after the addition of 60.0 mL of HI solution
