# A container has a volume of #4 L# and holds #3 mol# of gas. If the container is expanded such that its new volume is #16 L#, how many moles of gas must be injected into the container to maintain a constant temperature and pressure?

##### 1 Answer

Use the ideal gas law,

#### Explanation:

The ideal gas law is

If the volume increases from

The "new"

However, the answer is *already 3 moles* , so an *additional 9 moles* must be injected to give you a *sum* of *12 moles* .

The answer is therefore