Gases

Question 1

What must temperature be in for ALL gas laws?

Answer 1

Kelvin (k)

Question 2

How do you calculate changes in a gas?

Answer 2

The combined gas law.

P1V1/T1 = P2V2/T2

Question 3

How do you calculate things about a gas NOW?

Answer 3

The ideal gas law.
PV = nRT
R = .08206
Also
PV = mRT/M   and   P = DRT/M

Question 4

How do you calculate partial pressures?

Answer 4

Use P = nRT/V for each gas.

Just PV = nRT arranged for pressure

Question 5

What is the mole fraction?

How do you calculate it?

Answer 5

Ratio of gas to mixture of gases.

Divide the partial pressure by the total pressure or moles by total moles

Question 6

What are 4 assumptions of the kinetic molecular theory?

Answer 6

1. Gases are in constant, random motion
2. Pressure is a result of collisions with the container walls
3. There are no intermolecular forces (untrue)
4. Volume of molecules is negligible (also untrue)

Question 7

How do you calculate the root mean square speed?

Answer 7

Maxwell’s equation.
Urms = (3RT/M)^(1/2)
R = gas constant (8.314)

Question 8

What is diffusion?

Answer 8

Gradual mixing of different gases

Question 9

What is effusion?

Answer 9

Movement of gas through a small hole

Question 10

How do you calculate molar mass / identity of the gas from effusion?

Answer 10

Graham’s law

Rate1/Rate2 = (M2/M1)^(1/2)