A mixture of H2 and water vapor is present in a closed vessel at 20°C. The total pressure of the system is 755.0 mmHg.

Partial pressure of water vapor at 20°C equals 17.5 mmHg.

What is the partial pressure of H2?

Partial pressure of hydrogen gas in the mixture  is 732.5 mm Hg.

Explanation:

Data given:

total pressure of the system = 755 mm Hg

partial pressure of water vapour, pwater vapour = 17.5 mmHg

partial pressure of hydrogen gas, phydrogen gas = ?

temperature of the system = 20 degrees

According to Dalton law of pressure, the pressure exerted by each gas is independent and individual.

The total pressure is the sum of partial pressures of gases present in a mixture.

Ptotal = pwater vapour + p hydrogen gas

phydrogen gas  = P total - p water vapour

p hydrogen gas = 750 - 17.5

phydrogen gas = 732.5 mm Hg.

thus the partial pressure of the hydrogen gas in the mixture is 732.5 mm Hg.