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. The vapour pressure of water in the solutions is

Question

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. The vapour pressure of water in the solutions is (A) 43.4 mm (B) 13.5 mm (C) 25 mm (D) 23.4 mm

Tardigrade Admin · Accepted Answer

Given, P° = 23.8 mm w2 = 50 g, M2 (urea) = 60 g mol -1, Ps = ? (P° - Ps/P°) =? w1 = 850 g, M1 (water ) = 18 g mol-1 ∴ n2 = (50/60) = 0.83 ∴ n1 = (850/18) = 47.22 Applying Raoultâs law, (P° - Ps/P°) =(n2/n1 + n2) or (P° - Ps/P°) = (0.83/47.22 + 0.83) = (0.83/48.05) = 0.017 P° - Ps = 0.017 × 23.8 or Ps = 23.8 - 0.017 × 23.8 or Ps = 23.4 mm

Q. Vapour pressure of pure water at $298 K$ is $23.8 mm H g .$
$50 g$ of urea $(N H_{2} CON H_{2})$ is dissolved in $850 g$ of water. The vapour pressure of water in the solutions is

$43.4 mm$

$13.5 mm$

$25 mm$

$23.4 mm$

Q. Vapour pressure of pure water at 298K is 23.8mmHg. 50g of urea (NH2​CONH2​) is dissolved in 850g of water. The vapour pressure of water in the solutions is

43.4mm

13.5mm

25mm

23.4mm

Q. Vapour pressure of pure water at $298 K$ is $23.8 mm H g .$
$50 g$ of urea $(N H_{2} CON H_{2})$ is dissolved in $850 g$ of water. The vapour pressure of water in the solutions is

$43.4 mm$

$13.5 mm$

$25 mm$

$23.4 mm$