Answer to Question #262118 in General Chemistry for Angela

Question

A mixture of hydrogen gas and oxygen gas exerts a total pressure of 3.0 atm on the walls of its containee. If the partial pressure of hydrogen is 1.65 atm, find the mole fraction of oxygen in the mixture.

Answer 1

Q262118

A mixture of hydrogen gas and oxygen gas exerts a total pressure of 3.0 atm on the walls of its container. If the partial pressure of hydrogen is 1.65 atm, find the mole fraction of oxygen in the mixture.

Solution :

First, we will find the partial pressure of the Oxygen gas.

There is only hydrogen and oxygen gas in the mixture, so

Total Pressure = Partial pressure of H₂ + Partial pressure of O₂.

Total pressure = 3.0 atm, Partial pressure = 1.65 atm.

plug this information in the formula and find the Partial pressure of O₂.

3.0 atm = 1.65 atm + Partial pressure of O₂.

Partial pressure of O₂ = 3.0 atm - 1.65 atm = 1.35 atm.

Next, using the partial pressure of O₂ and Total pressure, we can find the mole fraction of O₂ in the mixture.

$$mole \ fraction \ of \ O_2 = \frac{Partial \ pressure \ of \ O_2}{Total Pressure }$$

Partial pressure of O₂ = 1.35 atm.

Total pressure = 3.0 atm

plug this in the equation we have

$$mole \ fraction \ of \ O_2 = \frac{1.35 \ atm }{3.0 \ atm } = 0.45$$

Mole fraction is a unitless quantity.

Hence the mole fraction of O₂ in the mixture is 0.45.