Question

A molecule M associates in a given solvent according to the equation \[\ce{M <=> (M)_n}\]. For a certain concentration of M, the van't Hoff factor was found to be 0.9 and the fraction of associated molecules was 0.2. The value of n is ______.

Options

• 3

• 5

• 2

• 4

Answer 1

A molecule M associates in a given solvent according to the equation \[\ce{M <=> (M)_n}\]. For a certain concentration of M, the van't Hoff factor was found to be 0.9 and the fraction of associated molecules was 0.2. The value of n is 2.

Explanation:

	nm	⇌	(M)n
initial	1		0
final	1 - α		α/n

i = `(1 - alpha + alpha//n)/1`

⇒ 0.9 = 1 - 0.2 + 0.2 / n

⇒ n = 2.