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 #12 L#, how many moles of gas must be injected into the container to maintain a constant temperature and pressure?
We can solve this problem by using the quantity-volume relationship of gases, illustrated by Avogadro's law:
We need to find the new quantity of gas when the volume is increased from
This is the total number of moles that satisfies the equation; we're asked to find how many need to be injected. The number of moles that you need to add is simply the total final moles minus the initial moles:
Thus, you need to inject