In an experiment, hydrogen is collected in a 455-milliliter jar above water at a pressure of 101,3 kilopascals and a
temperature of 29.1°C. In addition to hydrogen, there is some water vapor in the jar. If the partial pressure of the water vapor is 4.0 kilopascals, how many moles of hydrogen are generated during the experiment?

n = 1.9 ×10⁻⁵ mol

Explanation:

Given data:

Volume of hydrogen gas = 455 mm

Pressure of hydrogen gas = 101.3 kpa

Temperature = 29.1°C

Partial pressure of water vapor = 4.0 kpa

Number of moles of hydrogen gas = ?

Solution:

First of all we will convert the units.

Pressure of hydrogen gas = 101.3 kpa= 101.3/101 =  1 atm

Partial pressure of water vapor = 4.0 kpa = 4.0/ 101 = 0.04 atm

Temperature = 29.1 + 273 = 302.1 K

Volume of hydrogen gas = 455 / 1×10⁶ = 0.000455 L

Now we will calculate the total pressure.

Total pressure = Partial pressure of hydrogen gas + partial pressure of water vapors

Total pressure = 1 atm + 0.04 atm

Total pressure = 1.04 atm

Now we will calculate the number of moles;

PV = nRT

n = PV/RT

n =  1.04 atm × 0.000455 L / 0.0821 atm.L / mol.K × 302.1 K

n = 0.00047 /24.80/mol

n = 1.9 ×10⁻⁵ mol