The pressure of 1 mol oh gas is decreased to 0.5 atm at 273 K. What happens to the molar volume of the gas under these conditions?

A) the molar volume is halved

B) the mileage volume is doubled

C) the molar volume is tripled

D) the molar volume stays same

Answer is: B) the molar volume is doubled.

Boyle's Law (the pressure-volume law) : volume of a given amount of gas held at constant temperature varies inversely with the applied pressure when the temperature and mass are constant.

p₁V₁ = p₂V₂ (the product of the initial volume and pressure is equal to the product of the volume and pressure after a change).

For example:

p₁ = 1.0 atm; initial pressure.

Molar volume on standard temperature and pressure is Vm = 22.4 L/mol.

n = 1 mol; amount of the gas.

V₁ = 22.4 L/mol : 1 mol.

V₁ = 1 L; initial volume.

p₂ = 0.5 atm; final pressure.

1.0 atm · 22.4 L = V₂ · 0.5 atm.

V₂ = 1 atm · 22.4 L / 0.5 L.

V₂ = 44.8 L; final volume.

Vm = 44.8 L/mol.