Question

a sample of h2 gas is collected over water at 23 degrese celsius, if the observed pressure is 750.0 torr, calculate the partial pressure of h2

Answer 1

Answer:

728.9 torr

Explanation:

Collecting a gas over water results in gathering a mixture of gases. First of all, the target gas is collected, but the gathered sample also contains saturated water vapor.

The saturated water vapor always produces the same pressure which depends on temperature. At a given temperature of 23 degrees Celsius, the saturated vapor pressure is equal to 21.1 torr.

The total pressure is equal to the sum of partial pressures of water and hydrogen:

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

Solving for the partial pressure of hydrogen:

$p_{H_2} = p - p_{H_2O} = 750.0~torr - 21.1~torr = 728.9~torr$