The degree of dissociation `(alpha)` of a weak electrolyte `A_(x)B_(y)` is related to van't Hoff factor (i) by the expression

Options

A. `alpha = (i-1)/(x + y +1)`
B. `alpha = (x + y - 1)/(i - 1)`
C. `alpha = (x + y + 1)/(i-1)`
D. `alpha = (i-1)/(x + y -1)`

Answer

D

Explanation

`A_(x) B_(y) hArr xA^(y+) + y B^(x-) "Moles at eqm". 1-1 - alpha x alpha y x`
`:. i=(1-alpha) + x alpha +y alpha`
` or i = 1 = alpha (x+y-1) or alpha = (i-1)/(x + y - 1)`