Question

A high-pressure tank stores 70 g of hydrogen gas. Under similar conditions of temperature and pressure, the same tank stores 350 g of a gas A and 560 g of a gas B. Find the relative molecular masses of the gas.

Answer 1

Under the same conditions of temperature and pressure, the same tank contains the same number of moles of each gas. Therefore, the masses are proportional to their molecular masses.

For hydrogen:

Molecular mass of H_2​ = 2

For gas A:

`M_A/2 = 350/70`

M_A = 2 × 5

M_A = 10

For gas B:

`M_B/2 = 560/70`

M_B = 2 × 8

M_B = 16

Relative molecular mass of gas A = 10​

Relative molecular mass of gas B = 16​