Calculate the vapour pressure of a solution at 1000C containing 3g of cane sugar in 33g of water. (At wt. C = 12 , H = 1 , O = 16)

Question

Calculate the vapour pressure of a solution at 100°C containing 3g of cane sugar in 33g of water. (At wt. C = 12 , H = 1 , O = 16)

(A) 760 mm 

(B) 756.90 mm 

(C) 758.30 mm 

(D) None

Answer 1

Correct Option (B) 756.90 mm 

Explanation:

Vapour pressure of pure water (solvent) at 100°C, p⁰ = 760 mm.

Vapour pressure of solution, p = ?

Wt. of solvent , W = 33g

Wt. of solute , w = 3g

 Mol. wt. of water (H₂O), M = 18

Mol. wt. of sugar (C₁₂H₂₂O₁₁),

m = 12 x 12 + 22 x 1 + 11 x 16 = 342

According to Raoult’s law ,

= 760 – 3.19 = 756.90mm