Question

A container has a volume of `18 L` and holds `9 mol` of gas. If the container is compressed such that its new volume is `8 L`, how many moles of gas must be released from the container to maintain a constant temperature and pressure?

Answer 1

When pressure and temperature are held constant, the number of moles is proportional to the volume of the container.

Explanation:

Note that in this example, the number of moles is exactly half the number of liters.

The initial condition is `(9mol)/(18L)=0.5 (mol)/L`.
The final condition is `0.5 (mol)/L times 8L = 4 mol`.