Question

A sample of oxygen gas occupies a volume of 250. mL at 100 kPa pressure. What volume will it occupy at 200 kPa pressure?

Answer 1

The new volume of `"O"_2"` is `"125 mL"`.

Explanation:

This is an example of Boyle's law, which states that the volume of a gas varies inversely with pressure, as long as temperature and amount are kept constant. The equation to use for this law is `P_1V_1=P_2V_2`, where `P_1` is the initial pressure, `V_1` is the initial volume, `P_2` is the final pressure, and `V_2` is the final volume.

Known
`P_1="100 kPa O"_2"`
`V_1="250 mL O"_2"`
`P_2="200 kPa O"_2"`

Unknown
`V_2="???"`

Solution
Rearrange the equation to isolate `V_2`. Substitute the known values into the equation and solve.

`P_1V_1=P_2V_2`

`V_2=(P_1V_1)/P_2`

`V_2=(100 cancel"kPa"xx250 "mL")/(200 cancel"kPa")="125 mL O"_2"`