When the Ka value for CH3NH2 = 2.27 x 10 ^-11
and when we have the Ka value so, we can get Pka from this formula:
Pka = -㏒Ka
∴Pka = -㏒ (2.27 x10^-11)
= 10.6
now, to get the base/acid ratio by using Henderson-Hasselblach equation:
PH = Pka + ㏒[base/acid]
so by substitution:
10.22 = 10.6 + ㏒[base/acid]
∴[base/acid] = 0.417
∴[CH3NH2/CH3NH3Cl] = 0.417
