B= base morfina
BH+ = acido coniugato

BH+ + H2O <-> B + H3O+

Kh= [H3O+]^2/ Ca = kw/kb
Kh= 10^-14/ 1,62* 10^-6 = 6,17*10^-9

Da cui:
[H3O+]= radice quad. Kh*Ca
[H3O+]= radice quad. 6,17*10^-9* 0,2= 3,51*10^-5

pH = -log 3,51*10^-5 = 4,45