Question

Oxygen gas is collected over water. The atmospheric pressure is 748 mmHg, and the temperature of the oxygen is 29 ºC. The pressure of evaporating water at that temperature is 30.0 mmHg. What is the pressure of the oxygen gas collected?

Answer 1

The pressure of the oxygen gas collected : 718 mmHg

Further explanation

Given

P tot = 748 mmHg

P water vapour = 30 mmHg

Required

P Oxygen

Solution

Dalton's law of partial pressures states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases

Can be formulated:

P tot = P1 + P2 + P3 ....

The partial pressure is the pressure of each gas in a mixture

P tot = P H₂O + P Oxygen

P Oxygen = 748 mmHg - 30 mmHg

P Oxygen = 718 mmHg