A sample of Ar gas has a volume of 6.30 L with an unknown pressure. The gas has a volume of 8.57 L when the pressure is 2.74 atm, with no change in temperature or amount of gas. What was the initial pressure, in atmospheres, of the gas?

3.73 atm

Explanation:

Since there is no change in temperature, we use Boyle's law.

P₁V₁ = P₂V₂ where P₁ = initial pressure of Ar gas = unknown, P₂ = final pressure of Ar gas = 2.74 atm, V₁ = initial volume of Ar gas = 6.30 L and V₂ = final volume of Ar gas = 8.57 L

P₁ = P₂V₂/V₁ = 2.74 atm * 8.57 L/6.30 L = 3.73 atm