What is the mole fraction of oxygen in a gas mixture that is 37% oxygen and 63% nitrogen by volume?

If you have a sample of the gas solution that contains exactly 100 moles of gas. 37% of the volume (and therefore 37% of the moles of gas) is oxygen.

So:

37 moles of oxygen in 100 moles of solution. The mole fraction = 37/100 = 0.37. The same occur with the nitrogen: 63/100: 0.63, 63 moles of nitrogen in 100 moles of solution.

Explanation:

Avogadro's hypothesis can be stated in two ways:

1. Equal volumes of different gases, compared under the same conditions of temperature and pressure, contain the same number of molecules.

2. Equal numbers of molecules of different gases, compared under the same conditions of temperature and pressure, occupy equal volumes.

Another relationship, known as Avogadro's Law, is deduced from Avogadro's hypothesis, whose statement is:

The volume of a gas maintained at constant temperature and pressure is directly proportional to the number of moles of the gas.

The mole fraction of oxygen in the gas mixture is 0.37.

Explanation:

Mole fraction of oxygen is given as percentage by volume of oxygen divided by percentage by volume of gas mixture

percentage by volume of oxygen = 37% = 0.37

percentage by volume of gas mixture = 37% oxygen + 63% nitrogen = 100% = 1

Mole fraction of oxygen = 0.37 : 1 = 0.37