Chemistry question

Question

A sample containing 7.60 g O2 gas has a volume of 27.0 L . Pressure and temperature remain constant What is the new volume if 0.700 mole O2 gas is added

Answer 1

Time # 1:

m = 7.60 g

V = 27.0 L

Calculate the number of moles by dividing the mass *7.60 g) by the molar mass (15.999 x 2) = 31.998 g/mol to get 0.2375 moles

Time #2:

n = 0.2375 + 0.700 = 0.9375 moles

Using the ideal gas law:

PV = nRT with "R" being a constant.

So P/(RT) = n/V

For Time #1: P₁(RT₁) = n₁/V₁

And for Time #2: P₂(RT₂) = n₂/V₂

In both Time #1 and Time #2, P/(RT) are constants that remain the same therefore given that P₁(RT₁) = P₂(RT₂) then:

n₁/V₁ = n₂/V₂

or V₂ = n₂V₁/n₁

V₂ = (0.9375)(27.0)/(0.2375)

V₂ = 106.57 or, when rounded to the appropriate number of sig figs: V₂ = 107 L