# A gas occupies 175 mL at a pressure of 825 torr. What is the volume when the pressure is decreased to 415 torr?

Dec 2, 2014

The new volume will be $\text{348 mL}$.

#### Explanation:

You will need to use Boyle's law to answer this question. Boyle's law states that when temperature is constant, the volume of a gas is inversely proportional to the pressure. This means that if the volume increases, the pressure decreases and vice versa. The equation for Boyle's law is:

${P}_{1} {V}_{1} = {P}_{2} {V}_{2}$.

Given:

${P}_{1} = \text{825 torr}$

${V}_{1} = \text{175 mL}$

${P}_{2} = \text{415 torr}$

Unknown:

${V}_{2}$

Solution:

Isolate ${V}_{2}$ by dividing both sides of the equation by ${P}_{2}$, then solve for ${V}_{2}$.

V_2 = (P_1V_1)/P_2 =(825color(red)cancel(color(black)("torr"))xx175"mL")/(415color(red)cancel(color(black)("torr")))="348 mL"