A30.0 ml sample of hydrogen gas (h2) is collected over water at 20.00∘c and has a total pressure of 700.0 torr. the partial pressure of water vapor at 20.00∘c is 17.5 torr. calculate the mole fraction of h2 gas in the sample.

The mole fraction of hydrogen gas at 20°C is 0.975  

Explanation:

We are given:

Vapor pressure of water vapor at 20°C = 17.5 torr

Total pressure at 20°C = 700.0 torr

Vapor pressure of hydrogen gas at 20°C = (700.0 - 17.5) torr = 682.5 torr

To calculate the mole fraction of hydrogen gas at 20°C, we use the equation given by Raoult's law, which is:

where,

= partial pressure of hydrogen gas = 682.5 torr

= total pressure = 700.0 torr

= mole fraction of hydrogen gas = ?

Putting values in above equation, we get:

Hence, the mole fraction of hydrogen gas at 20°C is 0.975

1 is the answer to this problem