# A container has a volume of 18 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?

May 3, 2017

The number of moles to be injected is $= 5 m o l$

#### Explanation:

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

Initial volume is ${V}_{1} = 18 L$

Initial number of moles ${n}_{1} = 15 m o l$

Final volume is ${V}_{2} = 24 L$

Final number of moles is

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

$= \frac{24}{18} \cdot 15$

$= 20 m o l$

Number of moles to be injected is $= {n}_{2} - {n}_{1} = 20 - 15 = 5 m o l$