Question

A sample of gas has a volume of 200 mL at a pressure of 700 mm Hg. What will be its pressure if its volume is reduced to 100 mL?

Answer 1

The new pressure will be `"1000 L"`, rounded to one significant figure.

Explanation:

Boyle's law states that when a gas is held at a constant temperature and mass in a closed container, the volume and pressure vary inversely. The equation to use is `P_1V_1=P_2V_2`.

Given
`V_1=200cancel"mL"xx(1"L")/(1000cancel"mL")="0.2 L"`
`P_1="700 mmHg"`
`V_2=100cancel"mL"xx(1"L")/(1000cancel"mL")="0.1 L"`

Unknown
`P_2`

Equation
`P_1V_1=P_2V_2`

Solution
Rearrange the equation to isolate `P_2` and solve.

`P_2=(P_1V_1)/(V_2)`

`P_2=((700"mmHg"xx0.2cancel"L"))/(0.1cancel"L")="1400 L"`, which must be rounded to `"1000 L"` because all of the measurements have only one significant figure.