Question

A volume of a gas is 20.4 L when the pressure is 925 kPa. At constant temperature, a change in pressure causes the volume of the sample to change. If the new volume is 30.6 L, what is the new pressure?

Answer 1

`"617 kPa"`.

Explanation:

This is what we're given:

• `V_1`, or initial volume of `"20.4 L"`.
• `P_1`, or initial pressure of `"925 kPa"`.
• `V_2`, or final volume of `"30.6 L"`.

We have to find `P_2`, or the final pressure—to do this, we can use Boyle's law!:

`P_1V_1 = P_2V_2`

We can rearrange this to have only `P_2` on one side:

`P_2 = (P_1V_1)/V_2`

Plugging in all of the values, we get:

`(P_1V_1)/V_2 = ("925 kPa" xx "20.4" cancel("L"))/("30.6" cancel("L"))`

`P_2 = "616.667 kPa"`

Rounding this off to `3` significant figures (which has what has been given to us in the question), we get `"617 kPa"`. :)