Chapter 10

Question 1

What is a gas?

Answer 1

a phase of matter; composed of particles that are moving randomly and very fast in their containers

Question 2

Gas particles move in _____ lines until they collide with either the container wall or another particle; then they bounce off

Answer 2

straight

Question 3

A gaseous atom or molecule exerts a force when it collides with a _____ or _____
Molecular collisions are _____

Answer 3

surface or other gaseous particles

pressure

Question 4

the force exerted per unit area by gas molecules as they strike the forces around them

Answer 4

pressure

Question 5

Pressure =

Answer 5

F/A; Force/Area

Question 6

Gas pressure is a result of the constant ______ of the gas molecules and their _____ with the surfaces around them

Answer 6

movement; collisions

Question 7

The pressure of a gas depends on what three factors?

Answer 7

1. number of gas particles in a given volume
2. volume of the container
3. average speed (temp) of the gas particles

Question 8

A model for gases built on the idea that matter is particulate and its structure affects properties

Answer 8

Kinetic Molecular Theory

Question 9

The Kinetic Theory of Gases is based on these 3 assumptions

Answer 9

1. size of a particle is negligibly small (argon gas - 0.01% of the volume at normal pressure)
2. The average kinetic energy of a particle is proportional to the temperature in Kelvins (The motion is due to thermal energy which is spread out among the particles of gas)
3. Collisions of gas particles with each other and/or surfaces are said to be elastic (no exchange of energy occurs)

Question 10

What are the four basic properties of gas?

Answer 10

1. Pressure(P) - Units in atmospheres (atm)
2. Volume (V) - Units in liters (L)
3. Temperature(T) - Units in Kelvin (K),
   
   • where Kelvin (K) = Celsius T+ 273
4. Amount in moles (n)

Question 11

The properties of gas are interrelated; when one changes, ______
The simple gas laws describe the relationships between ____ of these properties
- investigate two properties and keep the other two _____

Answer 11

it affects the others
pairs
constant

Question 12

Boyle’s Law investigates _____

Answer 12

pressure and volume relationship

Question 13

Charles’ Law investigates _____

Answer 13

volume and temperature relationship

Question 14

Avogadro’s Law investigates _____

Answer 14

volume and amount (mole) relationship

Question 15

Boyle’s Law states that pressure and volume are _____ related. Formula?

Answer 15

inversely

PiVi = PfVf

Question 16

How do you find the volume of a cylinder?

Answer 16

V = pir^2h (pi x radius squared x height)

Question 17

Charles’ Law states that volume and temperature are ______. Formula?

Answer 17

proportional.

Vf/Tf = Vi/Ti

Question 18

According to Charles’ law, as a gas becomes colder, the volume of gas will ______ until ________

Answer 18

decrease/ the gas has no volume

Question 19

Avogadro’s law states that volume and amount of moles are ______

Answer 19

proportional

Question 20

All gases should roughly occupy the same volume under the same conditions of pressure and temperature. This is called the ________

Answer 20

molar volume

Question 21

The molar volume of gases at 0 degrees C and 1 atm is approximately _____

Answer 21

22 L/mol

Question 22

A hypothetical gas whose molecules occupy negligible space and have no interactions

Answer 22

ideal gas

Question 23

The simple gas law relationships discussed so far can be combined into a single law that encompasses all of them This is the _______

Answer 23

ideal gas law

PV = nRT

Question 24

What is the gas constant?

Answer 24

0.08206 L x atm/ mol x K

Question 25

How do you find the volume of a sphere? cube?

Answer 25

sphere: V = 4/3 pi r^3 (four thirds x pi x radius cubed) cube: area^3

Question 26

Because the volume of a gas varies with pressure and temperature, chemists have agreed on a set of conditions with which to report our measurements so that comparison is easy. These are called _______

Answer 26

standard conditions (STP)

Question 27

What are the standard conditions (STP)?

Answer 27

1. Standard pressure = 1 atm 2. Standard temperature = 273 K = 0 °C 3. Standard amount = 1 mol 4. Standard volume = 22.4 L - The volume occupied by one mole of a substance is its molar volume at STP (T= 273 K or 0 °C and P= 1atm)

Question 28

The volume of one mole of gas at STP is called the _______ _______ molecules of gas –Note that the type of gas is immaterial

Answer 28

molar volume | 6.022 ×10^23

Question 29

In the balloons above with 22.4 L of gas, which balloon is the heaviest? a) Balloon of helium b) Balloon of methane (CH4) c) Balloon of xenon d) All balloons weigh the same

Answer 29

balloon of xenon - biggest molar mass

Question 30

_____ is the ratio of mass to volume (mass/volume)

Answer 30

Density

Question 31

Density of a gas is generally given in ______ The mass of 1 mol = ______ The volume of 1 mol at STP = ____

Answer 31

grams/liter (g/L) molar mass 22.4 L

Question 32

Many gas samples are not pure but are mixtures of gases. Dry air, for example, is a mixture containing nitrogen, oxygen, argon, carbon dioxide, and a few other gases in trace amounts. In certain applications, the mixture can be thought of as _______

Answer 32

one gas

Question 33

Even though air is a mixture, its pressure, volume, and temperature can be treated as being one substance. By knowing air’s pressure, volume, and temperature, the _______ in an air sample can be determined—even though they are different compounds.

Answer 33

total moles of molecules

Question 34

The pressure of a single gas in a mixture of gases is called its ___________

Answer 34

partial pressure

Question 35

The partial pressure of a gas can be calculated in either of the following two cases

Answer 35

1. A fraction of the mixture it composes and the total pressure are known 2. The number of moles of the gas in a container of a given volume and temperature is known

Question 36

The sum of the partial pressures of all the gases in the mixture equals the total pressure. This is known as ________ Gases behave independently.

Answer 36

Dalton’s law of partial pressures. | Ptotal= Pa+ Pb+ Pc+....

Question 37

How do you find mole fraction?

Answer 37

Divide mol of gas by the total mol

Question 38

Kinetic molecular theory (KMT) 1. Gases are composed of a large number of particles that behave like hard, spherical objects in a state of constant, random motion. 2. The particles move in a straight line until they collide with another particle or the walls of the container. 3. The particles are much smaller than the distance between particles. Most of the volume of a gas is therefore empty space –occupy no volume What are the next 3 assumptions?

Answer 38

4. There are no force of attraction between gas particles or between the particles and the walls of the container. 5. Collisions between gas particles or collisions with the walls of the container are perfectly elastic. None of the energy of a gas particle is lost when it collides with another particle or with the walls of the container. 6. The average kinetic energy of a collection of gas particles depends on the temperature of the gas and nothing else.

Question 39

When it comes to gas, increasing temperature ______ the speed.

Answer 39

increases

Question 40

On a number-speed graph, what does an increase in temperature do?

Answer 40

peak shifts to the right, curve broadens, peak flattens

Question 41

A particle possessing the average kinetic energy moves at this speed. Particle speeds are inversely related to particle mass.

Answer 41

Root-mean-square speed (u [subscript] rms)

Question 42

average KE =

Answer 42

1/2 x mu^2 x Root-mean-square speed (u [subscript] rms)

Question 43

When it comes to gas, increasing the mass _____ the speed

Answer 43

decrease

Question 44

the gradual dispersal of one substance through another substance.

Answer 44

diffusion

Question 45

Two processes, diffusion and effusion, show how the average speeds of gas molecules are related to ___________

Answer 45

molar mass and temperature

Question 46

molecules escape through a small hole in a barrier into a region of low pressure in ______

Answer 46

effusion

Question 47

rate of effusion is proportional to ____

Answer 47

1/ square root of molar mass

Question 48

Hydrogen and oxygen are trapped in a balloon at STP. The gases are allowed to escape via a tiny hole. Which one will escape first?

Answer 48

Hydrogen

Question 49

In reactions involving gaseous reactants or products, the quantity of a gas is often specified in terms of its volume at a given temperature and pressure. As noted earlier, stoichiometry involves relationships between amounts in moles. For stoichiometric calculations involving gases, we can use the ideal gas law to determine ______________

Answer 49

the amounts in moles from the volumes, or to determine the volumes from the amounts in moles.

Question 50

ideal gas law, n = ?

Answer 50

n = PV/RT

Question 51

Real gases often do not behave like ideal gases at ___________

Answer 51

high pressure or low temperature

Question 52

Ideal gas laws assume ____________ | at high pressure and low temperature, these assumptions are not valid

Answer 52

no attractions between gas molecules | gas molecules do not take up space.

Question 53

Deviations from an ideal gas is due to ____________, the attractions and repulsions between molecules.

Answer 53

intermolecular forces

Question 54

What equation was developed to better approximate gas behavior than the ideal gas law? What were the corrections made for? Formula?

Answer 54

Van Der Waals Equation correction for intermolecular forces and particle volume [P + a(n/V)^2] x [V - nb] = nRT