# Which change in conditions would increase the volume of a fixed mass of gas?

##### 1 Answer
Jun 8, 2018

Increase temperature $T$ or decrease pressure $P$.

#### Explanation:

We can use the Ideal Gas Equation to solve this question:

$P V = n R T$

Hre

• $P$ is pressure in $\text{Pa}$
• $V$ is volume in ${\text{m}}^{3}$
• $n$ is number of moles of gas
• $R$ is the universal gas constant, $\text{8.31 J/K mol}$
• $T$ is temperature in Kelvin

In your scenario, when mass is fixed, the number of moles will be fixed, too. So we can combine both constant terms $n$ and $R$ to give us:

$P V = k T$

where $k$ is a constant.

Now, since we want to work out how volume changes, let's put $V$ on the left-hand side and move $P$ to the right-hand side:

$V = \frac{k T}{P}$

So from the equation, we can deduce that in order to increase volume, we can either increase temperature $T$ or decrease pressure $P$.

Hope this helps!