10E - Real Gases

Question 1

Theory: What two assumptions are made of ideal gases?

Answer 1

1. Molecules occupy no space.
2. Molecules do not attract one another.

Question 2

Theory: When can real gases be approximated as ideal? Why?

Answer 2

At high T and low P, essentially following assumption of MKE theory.
At high T and low P, molecules interact less due high average KE and large space between molecules negates the size of the molecules.

Question 3

Theory: When are real gases most different from ideal?

Answer 3

At low T and High P.

Question 4

Def: What is Van der Waal’s gas equation? Define the Van der Waal’s constants and explain their effect on the equation.

Answer 4

(P - a(n^2/V^2))(V-nb)=nRT
a: Corrects for sticky interaction between molecules, which decrease P below ideal.
b: Corrects for the volume of gas molecules, which at smaller volumes, becomes less impactful (less moles).

Question 5

Theory: For an ideal gas, PV/nRT = 1. What do deviations in a non-ideal gas T vs P chart signify?

Answer 5

Positive: PV/nRT > 1, and increased importance of molecular size.
Negative: PV/nRT < 1, and increased importance of attractive forces.