One litre flask contains air, water vapour and a small amount of liquid water at a pressure of 200 mmHg. If this is connected to another one litre evacuated flask, what will be the final pressure of the gas mixture at equilibrium?

Q: One litre flask contains air, water vapour and a small amount of liquid water at a pressure of 200 mmHg. If this is connected to another one litre evacuated flask, what will be the final pressure of the gas mixture at equilibrium? Assume the temperature to be 50 oC. Aqueous tension at 50°C = 93 mmHg .

Solution The aqueous tension remains same in both the flask. Also flask are at same temperature

∴  P1 V1 = P2 V2

where P1 = 200 – 93 = 107

V1 = 1 litre

V2 = 2 litre

107 × 1 = P × 2

P = 53.5 mm

Since aqueous tension is also present in flask, equivalent to 93 mm

Pressure of gaseous mixture

= 93 + 53.5 = 146.5 mmHg