Ideal Gas Law and Oxygen Calculations

The molecular mass of oxygen (O2) is 28 g mol−1.

At 20 °C, the equivalent temperature in Kelvin is 293.15 K.

The mole fraction of oxygen in air is 0.32.

Using the ideal gas law, the number of moles of oxygen in 1 L of air at 20 °C and 1 atm is approximately 0.042 mol.

The mass of oxygen present in 1.0 L of air is 0.296 g.

Ideal gas Law

The ideal gas law is defined as PV = nRT
P represents pressure, V represents volume, n represents the number of moles of a substance, R represents the ideal gas constant, and T represents temperature
In this case, we are solving for the number of moles so the ideal gas law can be arranged to n = PV/RT
We are given a volume of 1.0 L, a pressure of 1.0 atm, and a temperature of 20 C
The temperature must be in Kelvin so we add 273.15 to 20 degrees C to get 293.15 K
The ideal gas constant R is 0.082 L atm mol−1 K−1
The number of moles of air calculated is 0.042 moles

Oxygen

The mole fraction of oxygen is 0.22, which means 22% of the air is Oxygen
To find the number of moles of oxygen, we multiply the mole fraction of oxygen by the total number of moles of air
The number of moles of oxygen is 0.00924 moles

Mass of Oxygen

The molecular mass of oxygen is 32 g/mol
We multiply the number of moles of oxygen 0.00924 mol by the molecular mass of oxygen, 32 g/mol, to get the mass of oxygen in 1 L of air
The mass of oxygen is 0.296 g

This quiz covers the application of the ideal gas law, specifically focusing on calculating the number of moles of air and oxygen. It includes problem-solving with variables such as pressure, volume, temperature, and molecular mass. Perfect for students learning about gas laws in chemistry.