# A container has a volume of 4 L and holds 2 mol of gas. If the container is expanded such that its new volume is 5 L, how many moles of gas must be injected into the container to maintain a constant temperature and pressure?

Feb 8, 2018

The number of moles is $= 0.5 m o l$

#### Explanation:

$\text{Volume"/"Number of moles" = "Constant}$

at $\text{Constant Temperature and Pressure}$

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

The initial volume is $= 4 L$

The initial number of moles is ${n}_{1} = 2 m o l$

The final volume is ${V}_{2} = 5 L$

The final number of moles is

${n}_{2} = {V}_{2} / {V}_{1} \cdot {n}_{1} = \frac{5}{4} \cdot 2 = 2.5 m o l$

The number of moles to be added is

$n = {n}_{2} - {n}_{1} = 2.5 - 2 = 0.5 m o l$