8: The Gas Phase Flashcards Preview

MCAT Chem > 8: The Gas Phase > Flashcards

Flashcards in 8: The Gas Phase Deck (20):
1

units of gas pressures

1 atm = 760 mmHg = 760 torr = 101.325 kPa

2

STP conditions

273 K, 1 atm, *not same as standard state conditions (298 K, 1 atm, 1 M)

3

ideal gas

represents a hypothetical gas with molecules that have no intermolecular forces and occupy no volume... real gases deviate at high pressures (low volumes) and low temperatures

4

ideal gas law

PV=nRT

  • R = 0.0821 L•atm/mol•K OR 8.314 J/K•mol
  • use ideal gas law to find molar mass or denisty 

5

denisty

density = mass/volume

density =m/V = PM/RT

6

combined gas law

A image thumb
7

Avogadro's Principle

as the number of noles of gas increases, the volume increases in direct proportion

n1/V1 = n2/V2

8

Boyle's law

derivation of the ideal gas law that states that pressure and volume are inversely related

P1V1 = P2V2

9

charles's law 

derivation of the ideal gas law that states that volume and temperature are directly proportional

V1/T1 = V2/T2

10

Gay-Lussac's law

temperaure and pressure are directly proportional

P1/T1 = P2/T2

11

Dalton's law of partial pressures

when one or more gas is in a container, each contributes to the whole as if it were the only gas present

PT = PA + PB + Pc + ...

PA = XAPT

XA = moles of gas A/total moles of gas

12

Henry's law

solubility of gas will increase with increasing partial pressure of gas 

[A] = Kx PA

[A]1/P1 = [A]2/P2

[A] is concentration of A in solution

 

13

kientic molecular theory

accounts for observed behavior of gases; cosiders gas molecules to be pointlike, columeess particles exhibiting no intermolecular forces that are in constant random motion and undergo only completely elastic collisions with the container or other gas particles 

14

average inetic energy of a gas particle

KE= 1/2 mv2= 3/2 KBT

  • the higher the temperature, the faster the molecules move. the larger the molecules, the slower they move

 

15

root-mean-square speed 

one way to define average speed

R = 8.313 J/mol•K

J=kg/mo;

A image thumb
16

Maxwell-Botlzmann distribution curve

shows distribution of gas particle speeds at a given temperature

17

18

Graham's law of diffusion and effusion

under isothermal and isobaric conditions, the rates at which 2 gases diffuse are inversely proportional their molar masses... both diffusion and effusion are slower for larger molecules

A image thumb
19

real gases

real gases deviate from ideal gas behavior when gas atoms/molecules are forced into close proximity under high pressure (low volume) or low temperature

  • real gas particles take up space and have intermolecular forces

20

van der waals equation of state

a and b are physical constants experimentally determined for each gas...

  • a corrects for the attractive forces between molecules
    • smaller for gases that are small and less polarizable, largest for polar molecules
  • b corrects for the volume of the molecules themselves

A image thumb