In one mixture of methane and ethane, 10% by volume is occupied by a lighter gas

In one mixture of methane and ethane, 10% by volume is occupied by a lighter gas, and in the other – a heavier one. What is the density of a heavier mixture over a lighter one?

For all gases, the amount of matter is 22.4 l / mol. Hence, in the first mixture, there is 9 mol of ethane per 1 mol of methane.

Let’s calculate the average molar mass of the first mixture.

M (CH4) * n + M (C2H6) * n = 16 * 0/1 + 30 * 0/9 = 28.6 g / mol.

Find the average molar mass of the second mixture.

M (CH4) * n + M (C2H6) * n = 16 * 0.9 + 30 * 0.1 = 17.4 g / mol.

Find out the density of a heavier mixture relative to a light one.

28.6 / 17.4 = 1.644