Question

Calculate the ratio of ch3nh2 to ch3nh3cl required to create a buffer with ph = 10.12.

Answer 1

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


`pH=pKa + log( ([CH_3NH_2])/(CH_3NH_3Cl) ) \\ \\ ([CH_3NH_2])/(CH_3NH_3Cl)= 10^(pH-pKa)= 10^(10,12-10,61)=0,32`

So, the ratio of CH₃NH₂ to CH₃NH₃Cl should be 0,32

Have a nice day!