Question

An aqueous solution containing 64 percent by weight of volatile liquid A of molecular mass 28 has pressure of 145mm the. vapour pressure of liquid is​

Answer 1

Given:

Mass % = 64 %

Molecular mass = 28 gm

Pressure, P⁰ = 145 mm Hg

To Find:

Vapour pressure of liquid.

Calculation:

Let the mass of solution be 100 g

⇒ Mass of A = 64 gm

& Mass of water = 36 gm

- No of moles of A = 64 / 28 = 2.286

- No of moles of water = 36 / 18 = 2

- Mole fraction, X = 2.286 / (2.286 + 2) = 2.286/4.286

⇒ X = 0.533

- Vapour pressure of A, P(A) = P⁰ × X = 145 × 0.533

⇒ P(A) = 77.285 mm Hg

- The. vapour pressure of liquid A is​ 77.285 mm Hg.