Question

A sample of gas contains 6.25 × 10-3 mol in a 500.0 mL flask at 265°C. What is the pressure of the gas in kilopascals? Which variables are given? pressure volume temperature moles

Answer 1

Which variables are given?

Answer:

volume

temperature

moles

Which variables are unknown?

Answer:

pressure

Select the correct algebraic form for the equation to be used for this calculation.

Answer:

p= nRT/V

Solve the problem for the pressure of oxygen.

Answer:

55.9 kPa

Answer 2

55.9 kPa; Variables given = volume (V), moles (n), temperature (T)

We must calculate p from V, n, and T, so we use the Ideal Gas Law:

pV = nRT

Solve for p: p = nRT/V

R = 8.314 kPa.L.K^(-1).mol^(-1)

T = (265 + 273.15) K = 538.15 K

V = 500.0 mL = 0.5000 L

∴ p = [6.25 x 10^(-3) mol x 8.314 kPa·L·K^(-1)·mol^(-1) x 538.15 K]/(0.5000 L) = 55.9 kPa