Vapour pressure of pure water at 298 K is 23.8 mm Hg. 50 g of urea (NH₂CONH₂) is dissolved in 850 g of water. Calculate the vapour pressure of water for this solution and its relative lowering.

Question

Vapour pressure of pure water at 298 K is 23.8 mm Hg. 50 g of urea (NH 2 CONH 2 ) is dissolved in 850 g of water. Calculate the vapour pressure of water for this solution and its relative lowering.

Philoid · Accepted Answer

Given,

Vapour pressure of water, P_I^o = 23.8 mm of Hg

Weight of water, w₁ = 850 g

Weight of urea, w₂ = 50 g

Molecular weight of water, M₁ = 18 g/mol

Molecular weight of urea, M₂ = 60 g/mol

n₁ = = 47.22 mol

n₂ = = 0.83 mol

We have to calculate vapour pressure of water in the solution p₁

By using Rault's therom,

(relative lowering)

P_I = 23.4 mm of Hg

Hence,

The vapour pressure of water in the solution is 23.4mm of Hg and its relative lowering is 0.0173.

Vapour pressure of pure water at 298 K is 23.8 mm Hg. 50 g of urea (NH2CONH2) is dissolved in 850 g of water. Calculate the vapour pressure of water for this solution and its relative lowering.

Vapour pressure of pure water at 298 K is 23.8 mm Hg. 50 g of urea (NH₂CONH₂) is dissolved in 850 g of water. Calculate the vapour pressure of water for this solution and its relative lowering.