# A container has a volume of 12 L and holds 15 mol of gas. If the container is expanded such that its new volume is 24 L, how many moles of gas must be injected into the container to maintain a constant temperature and pressure?

Nov 26, 2017

$\text{15 mol}$ of gas should be injected.

#### Explanation:

Avogadro's law: Equal volumes of all gases, at the same temperature and pressure, have the same number of molecules.

Mathematically,

V ∝ n

${V}_{2} / {V}_{1} = {n}_{2} / {n}_{1}$

n_2 = V_2/V_1 × n_1

${n}_{2} = \text{24 L"/"12 L" × "15 mol}$

${n}_{2} = \text{30 mol}$

$\Delta n = {n}_{2} - {n}_{1} = \text{30 mol" - "15 mol" = "15 mol}$