Question

a certain mass of gas occupies a volume of 4.5 l at 125 kpa and is expanded at a constant temperature until the pressure is 75 kpa. what is the final volume of the gas?
3.5 l
45 l
2.25 l
7.5 l

Explanation:

Step1: Identify the gas - law formula

For a gas at constant temperature, Boyle's law is $P_1V_1 = P_2V_2$.

Step2: Assign values

Let $P_1=125\ kPa$, $V_1 = 4.5\ L$, and $P_2 = 75\ kPa$. We need to find $V_2$.

Step3: Rearrange the formula to solve for $V_2$

$V_2=\frac{P_1V_1}{P_2}$.

Step4: Substitute values and calculate

$V_2=\frac{125\ kPa\times4.5\ L}{75\ kPa}=\frac{562.5}{75}\ L = 7.5\ L$.

Answer:

D. 7.5 L