Hello!
From tables, we know that the pKa for Methylamine CH₃NH₂ is 10,61. Now, we can apply the Henderson-Hasselbach's 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^{10,12-10,61}=0,32[/tex]
So, the ratio of CH₃NH₂ to CH₃NH₃Cl should be 0,32
Have a nice day!
