Chem - Ch 13.1, 14

Question 1

What are the 3 assumptions of kinetic theory as it applies to gases

Answer 1

particles in a gas are considered to be small hard spheres with an insignificant volume
motion of particles in a gas is rapid, constant, and random
all collisions between particles in a gas are perfectly elastic

Question 2

how do the particles of a gas travel

Answer 2

in straight-line paths until they collide with another particle or another object

Question 3

what is pressure

Answer 3

force per area

Question 4

what causes gas pressure

Answer 4

billions of rapidly moving particles in a gas simultaneously colliding with an object

Question 5

what is a vacuum

Answer 5

empty space

Question 6

what is a barometer

Answer 6

a device used to measure atmospheric pressure

Question 7

how does a barometer work

Answer 7

there is a mercury column in a tube. the height of the mercury column depends on the pressure exerted by particles in the air colliding with the surface of mercury in the dish

Question 8

what is the relationship between kinetic energy and kelvin temperature

Answer 8

the kelvin temp of a substance is directly proportional to the average kinetic energy of the particles of a substance

Question 9

what is compressibility

Answer 9

a measure of how much the volume of matter decreases under pressure

Question 10

why are gases easier to compress than liquids or solids

Answer 10

because of the space between the particles in a gas

Question 11

why do airbags work

Answer 11

the compression of the gas inside the airbag absorbs the energy of the impact

Question 12

what are the three factors that affect gas pressure

Answer 12

the amount of gas
the volume of gas
the temperature

Question 13

what is an example of the effect of the amount of gas on pressure

Answer 13

if you add more air into a raft, the pressure inside the raft will increase

Question 14

what is an example of the effect of the volume of gas on pressure

Answer 14

when a car piston forces gas into a smaller volume, the pressure increases

Question 15

what is an example of the effect of the temperature on pressure

Answer 15

a hot potato chip bag will bulge at the seams because and increase in temp causes an increase in pressure

Question 16

how are pressure and volume related

Answer 16

inversely proportional

Question 17

how are temperature and volume related

Answer 17

directly proportional

Question 18

what is so special about -273 degrees C

Answer 18

it is the same as 0 K

Question 19

why do you have to use K when solving gas law problems

Answer 19

it is not a direct relationship if temp is expressed in celsius
Kelvin is an absolute temperature scale that starts at 0

Question 20

how are pressure and temperature related

Answer 20

directly proportional

Question 21

how do pressure cookers reduce cooking time

Answer 21

they increase the pressure of the steam which raises the temperature of it which causes the food to cook faster

Question 22

what is the combined gas law

Answer 22

PV/nT = PV/nT

Question 23

what has to be constant throughout the combined gas law

Answer 23

units

Question 24

what is the ideal gas law

Answer 24

PV = nRT

Question 25

Under what conditions are real gases most likely to differ from ideal gases

Answer 25

At low temps and high pressures

Question 25

Under what conditions are real gases most likely to differ from ideal gases

Answer 25

At low temps and high pressures

Question 26

How is the total pressure of a gas mixture related to the partial pressures of the component gases

Answer 26

In a mixture of gases, the total pressure is the sum of the partial pressures of the gases

Question 27

What does gas pressure depend on

Answer 27

The number or particles in a given volume and the average kinetic energy of those particles

Question 28

How does Dalton's law of partial pressures hold true

Answer 28

Each component gas exerts it's own pressure independent of the pressure exerted by the other gases

Question 29

Does the kind of particle affect gas pressure

Answer 29

No, amount of gas and their avg KE does

Question 30

If the temperature of a fixed quantity of gas decreases, and the pressure remains unchanged, what happens to the volume

Answer 30

It decreases

Question 31

If the temperature of a fixed quantity and a fixed volume of gas changes, what also changes?

Answer 31

Pressure

Question 32

If the volume of a container of gas is reduced, what will happen to the pressure inside the container

Answer 32

The pressure will increase

Question 33

What happens to the pressure of a gas inside a rigid container if the temp of the gas decreases?

Answer 33

Pressure decreases

Question 34

If a balloon is heated, what happens to the volume of the air in the balloon if pressure is constant

Answer 34

It increases

Question 35

What is the combined gas law

Answer 35

PV/nT

Question 36

What is diffusion

Answer 36

The tendency of molecules to move towards ares of lower concentration until the concentration is uniform throughout

Question 37

What is effusion

Answer 37

When gas escapes from a tiny hole in its container

Question 38

What is Graham's law of effusion

Answer 38

The rate of effusion of a gas is inversely proportional to the square root of the gas's molar mass

Question 39

why did the can crush experiment work

Answer 39

the particles were heated up, and when it go put into the cold water, they cooled down so the internal pressure decreased causing the external pressure to crush it

Question 40

Increasing the volume of a given amount of gas at a constant temperature causes the pressure to decrease because why?

Answer 40

The molecules are striking a larger area w the same force

Question 41

Why does 19.0 grams of fluorine gas at stp contain the same number of molecules as 1/2 a mole of oxygen at stp

Answer 41

Because 19.0 of fluorine is 1/2 a mole of fluorine and 1/2 a mole of anything is always the same amount of molecules

Question 42

In class we put a marshmallow peep into a vacuum chamber & removed some of the air in the chamber. What happened to the marshmallow and why?

Answer 42

The marshmallow expanded as we continued taking air out of the chamber. As we removed air from the chamber, this decreased the pressure inside bc n and p are directly proportional. This decreased the external pressure on the peep. The volume of the peep increased in order to decrease it's internal pressure (since v and p are inversely proportional) so that the external and internal pressures could be balanced.

Question 43

You have two containers, each holding 1 mole of Xenon gas at 15°C. Container A has a volume of 3.0 L and container B has a volume of 1.0 L. How does the average kinetic energy of the xenon atoms compare between the two containers?

Answer 43

Same in both containers bc avg kinetic energy if particles is directly proportional to their kelvin temp and they both have the same kelvin temp since they are in the same environment

Question 44

You have two containers, each holding 1 mole of Xenon gas at 15°C. Container A has a volume of 3.0 L and container B has a volume of 1.0 L. Compare the forces with which the xenon atoms collide with the sides of each container

Answer 44

Same force bc the temp is the same, so their kinetic energies are the same, and they both have the same amount of molecules, so they are moving with the same speed/force

Question 45

You have two containers, each holding 1 mole of Xenon gas at 15°C. Container A has a volume of 3.0 L and container B has a volume of 1.0 L. Compare the pressures of the 2 xenon samples

Answer 45

Pressure in container A is less than that of container b bc CA has a bigger volume CB, and when n and t are constant, pressure and volume are inversely proportional