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

van't Hoff factor (i)=[1+(n−1)α]where, n = number of ions from one mole of solute α=degree of ionization/association AxBy⇌xA+yBTotal ions =(x+y)∴ i=1+(x+y−1)α∴ α=i−1(x+y−1)