Chapter 5 Gases

Question 1

Kinetic molecular theory

Answer 1

A model that views gases as a collection of particles in constant motion

Question 2

Pressure

Answer 2

A measure of force exerted per unit area. In chemistry, this is most commonly the force
exerted by gas molecules as they strike the surfaces around them

Question 3

The ideal gas law

Answer 3

PV = nRT. Relates the pressure, volume, temperature and amount of a gas

Question 4

The ideal gas constant

Answer 4

When used with the ideal gas law: 0.08206 Latm/molk. When used to calculate the
RMS velocity of gas particles: 8.314 J/mol*k .

Question 5

Standard temperature and pressure (STP)

Answer 5

273.15 K and 1.00 atm

Question 6

Molar volume at STP

Answer 6

One mole of any gas occupies 22.4 L at STP. Can be used to convert between
volume and moles of a gas.

Question 7

Mole fraction

Answer 7

The number of moles of a component in a mixture divided by the total number of moles
in the mixture

Question 8

Partial pressure

Answer 8

The pressure exerted by an individual gas within a mixture

Question 9

Dalton’s law of partial pressures

Answer 9

The law stating that the sum of the partial pressures of the
components in a gas mixture must equal the total pressure

Question 10

Root mean square velocity

Answer 10

A method of describing the speed at which gas particles travel.

Question 11

Mean free path

Answer 11

The average distance traveled by a gas particle between collisions

Question 12

Diffusion

Answer 12

The process by which gas particles spread out in response to a concentration gradient.

Question 13

Effusion

Answer 13

The process by which gas escapes from a container into a vacuum through a small hole

Question 14

Graham’s law of effusion

Answer 14

A scientific law that states the ratio of effusion rates of two gases is equal to
the square root of the inverse of their molar masses

Question 15

Elastic collisions

Answer 15

Collisions in which the total kinetic energy of the colliding bodies is the same before
and after the collision

Question 16

Real gases

Answer 16

Gas that behaves in a non-ideal manner because of intermolecular forces and particle
volume. All gases are technically real gases

Question 17

Use kinetic molecular theory to describe why gas assumes shape of containers

Answer 17

Gas are free to move past each other

Question 18

Use kinetic molecular theory to describe why gases are compressible

Answer 18

space between gases; external forces force gas particles closer together

Question 19

Use kinetic molecular theory to explain why gases exert pressure on their surroundings

Answer 19

colliding creates a small amount of force; gas colliding with surroundings is called pressure

Question 20

At higher temperatures, do gas particles have a higher or lower average velocity?

Answer 20

higher

Question 21

Do lighter gas particles, such as He, have a higher or lower average velocity than heavier gas particles, such as Xe?

Answer 21

higher

Question 22

What two assumptions are made about ideal gases

Answer 22

1.The volume of the gas particles is small relative to
the volume of the container
2.Collisions are perfectly elastic
(energy before = energy after

Question 23

Why do the volume of gas particles causes gases to behave in a non-ideal manner

Answer 23

The volume of gas particles adds to the total volume of the gas, therefore increasing the molar volume.

Question 24

Why do intermolecular forces (attractions between gas particles) causes gases to behave in a non-ideal
manner

Answer 24

cause some collisions between gas particles to be inelastic. results in fewer
collisions between the gas particles and their container, causing a decrease in pressure

Question 25

What pressure conditions cause gases to behave in a non-ideal manner

Answer 25

High

Question 26

What temperature conditions cause gases to behave in a non-ideal manner

Answer 26

Low

Question 27

molar volume conversion

Answer 27

1mol/22.4L and 22.4L/1 mol