Question

a sample of H2 is collected over water such that the combined hydrogen water vapor sample is held at a pressure of one standard atmosphere. what is the partial pressure of the H2 if that of the water vapor is 2.5 kPa

Answer 1

Answer : The partial pressure of $H_2$ is 98.825 kPa.

Solution : Given,

Total pressure of hydrogen water vapor = 1 atm = 101.325 kPa    (1 atm = 101.325 kPa)

Partial pressure of water vapor = 2.5 kPa

Dalton's law of partial pressure : It is defined as the total pressure exerted is equal to the sum of the partial pressure of individual gases.

Formula used :

$P_{Total}=\sum_{i=1}^nP_i$

$P_{Total}$ = Total pressure

$P_{i}$ = Partial pressure of individual gases

$P_{Total}=P_{H_2}+P_{\text{ Water vapor}}$

Now put all the given values in this expression, we get

$101.325kPa=P_{H_2}+2.5kPa$

$P_{H_2}=98.825kPa$

Therefore, the partial pressure of $H_2$ is 98.825 kPa.