Under what conditions will the gauge pressure of a cylinder of N2O accurately represent its contents?

Under what conditions will the gauge pressure of a cylinder of N2O accurately represents its contents?

I. When the liquid in the cylinder has completely vaporized.

II. When the ambient temperature exceeds the critical temperature.

III. When the filling density is less than 1.0 (water-filled).

The correct answer is

I. When the liquid in the cylinder has completely vaporized.

Explanation:

Raoult's law states that the vapour pressure (P1) of a solvent is the same as the vapour pressure of the pure solvent multiplied by fraction in moles of the solvent in the solution

That is P1 = X1 × P01

Where X1 = (Moles of solvent)/(moles of solvent + moles of solute)

When the solvent is pure, X1 = 1, and P1 = P01 That is the N2O has mole fraction is 1 when the N2O has completely evaporated into a pure solvent