# A container has a volume of 5 L and holds 1 mol of gas. If the container is expanded such that its new volume is 9 L, how many moles of gas must be injected into the container to maintain a constant temperature and pressure?

Jun 24, 2018

$0.8 m o l$

#### Explanation:

According to Ideal gas equation,

$P V = n R T$

$\Rightarrow \frac{n}{V} = \frac{P}{R T}$

So for constant pressure and temperature,

$\frac{P}{R T} = \text{constant}$

$\frac{{n}_{i}}{{V}_{i}} = \frac{{n}_{f}}{{V}_{f}}$

Put ${n}_{i} = 1 , {V}_{i} = 5 L , {V}_{f} = 9 L \text{ and } {n}_{f} = \left({n}_{i} + x\right)$

You will get $x$ as $0.8 m o l$