Question

When a chemist collects hydrogen gas over water, she ends up with a mixture of hydrogen and water vapor in her collecting bottle. If the pressure in the collecting bottle is 97.1 kilopascals and the vapor pressure of the water is 3.2 kilopascals, what is the partial pressure of the hydrogen?

Answer 1

Answer: The partial pressure of the hydrogen gas is 93.9 kiloPascals.

Explanation:

The partial pressure of the water vapors = $p_{H_2O,g}=3.2 kPa$

The partial pressure of the hydrogen gas = $p_{H_2}$

The pressure measured in the collecting bottle  = $p=97.1 kPa$

While collecting the hydrogen gas in a collecting bottle with amount of water vapors also get introduced. The total pressure in the collecting bottle will be due to partial pressures of the water vapors and hydrogen.

$p=p_{H_2O,g}+p_{H_2}$

$97.1 kPa=3.2 kPa+p_{H_2}$

$p_{H_2}=97.1 kPa-3.2 kPa=93.9 kPa$

The partial pressure of the hydrogen gas is 93.9 kiloPascals.