Hello!
The chemical reaction for the ionization of CH₃NH₂ is the following:
CH₃NH₂ + H₂O ⇄ CH₃NH₃⁺ + OH⁻ pKb=3,30
[tex]pKa=14-pKb=14-3,30=10,70[/tex]
Now we apply the Henderson-Hasselbach equation and clear for the ratio of CH₃NH₂ to CH₃NH₃Cl:
[tex]pH=pKa+log( \frac{[CH_3NH_2]}{[CH_3NH_3Cl]} ) \\ \\\frac{[CH_3NH_2]}{[CH_3NH_3Cl]}= 10^{(pH-pKa)}= 10^{(10,28-10,70)}=0,38[/tex]
So, the ratio of CH₃NH₂ to CH₃NH₃Cl is 0,38
Have a nice day!
