Question

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

Answer 1

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.

Step-by-step 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

Answer 2

When the ambient temperature exceeds the critical temperature

Step-by-step explanation:

The gas pressure within the cylinder of N2O is approximately 750 psig at 70⁰F. Because of the presence of liquid N2O in the cylinder, the gas pressure gauge on the cylinder will record full as long as any liquid remains in the cylinder. The gauge pressure will accurately represent the content of the cylinder when the the ambient temperature exceeds the critical temperature of the N2O.