Question

A solution of glycol containing 1.82 g/litre has an osmotic pressure of 51.8 cm of mercury at 10°C. What is the molecular weight of glycol?

Options

• 62.04

• 70.16

• 80.54

• 100.21

Answer 1

62.04

Explanation:

Given: Mass of glycol in 1 litre = 1.82 g

Osmotic pressure (π) = 51.8 cm Hg = `51.8/76` atm ≈ 0.6816 atm

Temperature (T) = 10°C = 283 K

R = 0.0821 

We know that 

`pi = n/V RT`

⇒ `pi = w/(M * V)RT`    ...(i)

Where,

w = 1.82 g

V = 1 L

M = Molecular weight of glycol

M = `(w RT)/(pi V)`    ...[From equation (i)]

= `(1.82 xx 0.0821 xx 283)/(0.6816 xx 1)`

= `42.286426/0.6816`

= 62.04