Question

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

Answer 1

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

Explanation:

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

`PV = nRT`

Hre

• `P` is pressure in `"Pa"`
• `V` is volume in `"m"^3`
• `n` is number of moles of gas
• `R` is the universal gas constant, `"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:

`PV = kT`

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 = (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!