Chapter 9 (Gases)

Question 1

What are the 6 Properties of Gas?

Answer 1

1. Neither definite in shape of volume.
2. Uniformly fills any container.
3. Exerts pressure on surroundings.
4. Change volume with temp. & pressure.
5. Miscible - mixes together in any proportion.
6. Much less dense than solids or liquids.

Question 2

Pressure is defined as?

Answer 2

The force exerted per unit area by gas molecules as they strike the surfaces around them. (Volume, temperature and the # of moles of gas present.)

Question 3

1 atm is equivalent to?

Answer 3

760 mmHg = 76 cmHg = 101,325 Pa
= 101.325 kPa = 29.92 inHg = 760 torr = 1.01325 bar = 1013.25 mbar = 14.7 psi

Question 4

Pressure as an equation?

Answer 4

P = F/A
Pressure is the ratio of force to the surface area over which force is applied.

Question 5

Amonton’s Law: Relating Pressure and Temperature.
Equation?
Constants?

Answer 5

P1/T1 = P2/T2
(n and V are constant)
(Pressure and Temperature are directly proportional)
P/T= constant

Question 6

Charles Law: Relating Volume and Temperature.
Equation?
Constants?

Answer 6

V1/T1 = V2/T2
(P and n are constant)
(Volume and Temperature are directly proportional)
V/T = constant

Question 7

Boyle’s Law: Relating Pressure and Volume.
Equation?
Constants?

Answer 7

P1V1 = P2V2
(n and T are constants)
(Volume is inversely proportional to Pressure)
PV = constant

Question 8

Avogadro’s Law: Relating Volume and n (moles).

Answer 8

V1/n1 = V2/n2
(T and P are constants)
(Volume is directly proportional to the # of moles of gas).
V/n = constant

Question 9

What is the Ideal Gas Law equation?
What do the constants stand for?
What is R?

Answer 9

PV = nRT
R= 0.08206 L• atm/ K• mol
P= pressure (atm)
V= volume (L)
n= moles
T= temperature (K)

Question 10

What is the Combined Gas Law?

Answer 10

PV/ nT= constant
(If n is constant)
PV/ T= constant

Question 11

Mole fraction is?

Answer 11

Ratio of the number of moles of a component in a mixture to the total number of moles in a mixture.
(Xa = na/ ntotal

Question 12

What is Diffusion?

Answer 12

The process by which gas molecules spread out in response to a concentration gradient.
(The spread of one substance through another).

Question 13

What is Effusion?

Answer 13

The process by which a gas escapes from a container through a small hole into a region of lower pressure.

Question 14

What characteristics do particles have during effusion and diffusion?

Answer 14

Heavier particles move more slowly, and thus will diffuse or effuse more slowly.

Question 15

What are the Ideal gas definitions?

Answer 15

1) no volume
2) random motion constant
3) kinetic to temperature are proportional
4) collision is elastic
5) no repulsive or attractive forces

Question 16

What is the Rate of diffusion and effusion equation?

Answer 16

Rx/Ry = sqrt(My) / sqrt(Mx

Rx/Ry = sqrt(3RT/Mx)/ sqrt(3RT/ My)

Question 17

Kinetic Molecular Theory (KMT) assumes that gas molecules?

Answer 17

1. Have tiny volumes compared with the collective volume they occupy.
2. Move constantly and randomly.
3. Have average kinetic energy that is proportional to absolute temperature.
4. Engage in elastic collision with walls of container and other gas molecules.
5. Act independently of other gas molecules; the pressure exerted by the gas is the result between the gas molecules and container walls.

Question 18

Boyle’s Law simple states..

Answer 18

Decreasing volume increases number of collisions per area; P increases.

Question 19

Dalton’s Law simple states..

Answer 19

Total Pressure depends only on total number of moles of gas, not on their identities.

Question 20

Avogadro’s Law simple states..

Answer 20

Increasing n increases the number of collisions; gas expands to keep pressure constant.

Question 21

Charle’s Law simple states..

Answer 21

Increasing T increases kinetic energy; force of collision increases and gas expands to maintain constant P.

Question 22

Amonton’s Law simple states..

Answer 22

Increasing T will increase force of collision if volume is kept constant; P will increase.