The Gas Phase

Question 1

important pressure equivalences:

1 atm = __ mmHg = __ torr = __ kPa

Answer 1

1 atm = 760 mmHg = 760 torr = 101.325 kPa

Question 2

measures incident (usually atmospheric) pressure; as pressure increases, more mercury is forced into column, increasing its height; as pressure decreases, mercury flows out of column under its own weight, decreasing its height

Answer 2

simple mercury barometer

Question 3

volume of equimolar gases at STP; regardless of identity of gas

Answer 3

1 mol = 22.4 L

Question 4

states that individual gas components of a mixture of gases will exert individual pressures in proportion of their mole fraction; total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases

Answer 4

Dalton’s law of partial pressures

Question 5

Dalton’s law of partial pressures

Answer 5

P(T) = P(A) + P(B) + P(C) + …

where:
P(T) = total pressure
P(A,B, or C) = partial pressure of the respective gas

Question 6

partial pressure of gas

Answer 6

P(A) = 𝛸(A) P(T)

where:
P(A) = partial pressure of gas A
𝛸(A) = mole fraction of gas A
P(T) = total pressure

Question 7

mole fraction of gas

Answer 7

𝛸(A) = (moles of gas A) / (total moles of gas)

where:
𝛸(A) = mole fraction of gas A

Question 8

the pressure exerted by evaporated particles above the surface of a liquid

Answer 8

vapor pressure

Question 9

states that the amount of gas dissolved in a solution is directly proportional to the partial pressure of that gas at the surface of a solution

Answer 9

Henry’s law

Question 10

Henry’s law

Answer 10

[A] = k(H) P(A) or A / P(1) = A / P(2) =k(H)

where:
[A] = concentration of A in solution
k(H) = Henry’s constant
P(A) = partial pressure of gas A

Question 11

attempts to explain behavior of gas molecules; four assumptions

Answer 11

kinetic molecular theory

Question 12

four assumptions of kinetic molecular theory:

Answer 12

1) gas particles have negligible volume
2) gas particles do not have intermolecular attractions or repulsions
3) gas particles undergo random collisions with one another and the walls of the container
4) the average kinetic energy of the gas particles is directly proportional to the temperature

Question 13

root-mean-square speed (u(rms))

Answer 13

u(rms) = √((3RT)/M)

where:
R = ideal gas constant
T = temperature
M = molar mass

Question 14

describes behavior of gas diffusion or effusion; states that gases with lower molar masses will diffuse or effuse faster than other gases with larger molar masses at the same temperature

Answer 14

Grahm’s law

Question 15

spreading of gas particles from high to low concentration

Answer 15

diffusion

Question 16

the movement of gas from one compartment to another through a small opening under pressure

Answer 16

effusion

Question 17

deviate from ideal behavior under high pressure (low volume) and low temperature conditions

Answer 17

real gases

Question 18

used to correct the ideal gas law for intermolecular attractions (a) and molecular volume (b)

Answer 18

van der Waals equation of state