The degree of dissociation (α ) of a weak electrolyte AxBy is related to Van't Hoff factor (i) by the expression

No.of particles in aq. sol. =(x+y)Let be degree of ionization of the electrolyte                                Before ionization;        1                 0                  0After ionization;         1-             x               ytotal no.of particles After ionization =1-+(x+y)i = 1+[(x+y)-1]