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Flashcards in Gas Phase Deck (21):
0

STP

273.15 K
1 atm = 760 mm Hg = 760 torr

Not to be confused with standard state!

1

Ideal Gas

Volume-less gas with no intermolecular forces used in calculations that behaves according to the kinetic molecular theory of gases as described by the ideal gas law.

2

What are the assumptions inherent in the Kinetic Molecular Theory of Gases?

• Volume-less particles
• Constant, random motion
• No intermolecular attractions
• Perfectly elastic collisions
• Average kinetic energy proportional to absolute temperature of gas

3

Ideal Gas Law

PV = nRT

4

Boyle's Law

Pressure is inversely proportional to Volume at constant Temperature.

PV = k

5

Gas Constant

8.21 X 10^-2 (L•atm)/(mol•K)
8.34 J/(K•mol)

6

Charles and Gay-Lussac's Law

Volume is directly proportional to its Temperature at a constant Pressure.
V/T = k

7

Avogadro's Principle

The number of moles present is directly proportional to the Volume of the gas at constant Temperature and Pressure. One mole of gas has a volume of 22.4 L.
n/V = k

8

How does the behavior of Real Gases differ from that of Ideal Gases as Pressure increases to condensation pressure?

As the pressure increases, particles are pushed closer together and intermolecular forces become stronger as the gas becomes a liquid.

9

At moderately high pressures (a few hundred atm), what happens to a real gas?

The volume will be less than that expected from the ideal gas law.

10

What happens to the Volume of a real gas at extreme pressures?

The molecules begin to expand, increasing the volume.

11

What happens to real gases as temperature decreases?

The average velocity decreases, leading to a smaller Volume, as the Temperature approaches the condensation point and intermolecular forces become stronger, forming a liquid.

12

Van der Waald equation

(P + ((a*n^2)/V^2))(V - nb) = nRT
a corrects for the attractive component
b corrects for the volume

13

Vapor Pressure

A vapor's partial pressure when in equilibrium with its liquid and solid state.

14

Partial Pressure or Dalton's Law of Partial Pressures

(Pressure of single gas) = (Total Pressure) (mole fraction of single gas)

mole fraction = (number of moles of gas)/(total number of moles)

Sum of partial pressures equals total pressures

15

Henry's Law

Dissolved gas pressure is directly proportional to gas partial pressure above solution.

16

Average speed of gases

|v| = (3RT/MM)^1/2

17

Kinetic Energy and Temperature of gas

KE = (1/2)mv^2 = (3/2)(Boltzmann's Constant) T

18

Graham's Law

R1/R2 = (MM2/MM1)^1/2
For effusion and diffusion

19

Diffusion

Passive transport through a medium due to random motion.

20

Effusion

Movement of a gas through a small opening to an area off lower pressure.