Chapter 8: The Gas Phase

Question 1

What is the mathematical realtionship between all the units of pressure?

Answer 1

1 atm = 760 mmHg = 760 torr = 101.325 kPa

Question 2

What is standard temperature and pressure?

Answer 2

1 atm and 273 K; occupies 22.4 L

Question 3

What is an ideal gas?

Answer 3

1. no intermolecular forces
2. occupy no volume

Question 4

What is the ideal gas law?

Answer 4

PV = nRT

Question 5

What are the units for the R gas constant?

Answer 5

L-atm/mol-K

make sure to convert all values to this before substituting

Question 6

Density is defined as What?

Answer 6

ratio of the mass per unit volume of substance

Question 7

Avogadro’s principle states what?

Answer 7

All gases at a constant temp and pressure occupy volumes that are directly proportional to the number of moles of gas present

Question 8

1 mol of any gas, irrespective of its chemical identity, will occupy how many liters at STP?

Answer 8

22.4

Question 9

Boyle’s law states?

Answer 9

Gas held at constant temperature will have volume inversely proportional to pressure

Question 10

Charles’s Law states?

Answer 10

At constant pressure, the volume of a gas is proportional to its absolute temperature

Question 11

Gay-Lussac’s law states?

Answer 11

At constant volume, pressure and temp are directly proportional

Question 12

Dalton’s law of partial pressures states?

Answer 12

the total pressure of a gaseous mixture is equal to the sum of the partial pressures of the individual components

Question 13

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

Answer 13

Vapor pressure

Question 14

Henry’s law: Henry noticed that, at various applied pressures, the ____________ of a gas in a liquid increased or decreased.

Answer 14

concentration

Question 15

Vapor pressure from evaporated molecules forces some of the gas back into liquid phase and equilibrium is reached between what two processes?

Answer 15

Evaporation and condensation

Question 16

Kinetic molecular theory makes 5 assumptions about ideal gas behavior. What are they?

Answer 16

1. Particle volume is negligible to container volume
2. No intermolecular attractions
3. Continuous random motion
4. All collisions are elastic - conservation of momentum and kinetic energy
5. Average kinetic energy is proportional to absolute temp of gas

Question 17

The speed of an individual gas molecule is impossible to define, so how do we define gas speed?

Answer 17

Average molecular speed

Question 18

What can we use to define average gas speed?

Answer 18

Root mean square speed

Question 19

What happens to molecules at higher temperatures?

Answer 19

A greater proportion move at higher speeds

Question 20

Kinetic molecular theory predicts that heavier gases diffuse (slower/faster)? than lighter ones because of their differing average speeds.

Answer 20

slower

Question 21

Because all gas particles have the same average kinetic energy at the same temperature, what must be true about particles with greater mass?

Answer 21

They travel at a slower average speed

Question 22

Under isothermal and isobaric conditions, the rates at which 2 gases diffuse are inversely proportion to what?

Answer 22

The square roots of their molar masses

Question 23

____________ is the flow of gas particles under pressure from one compartment to another through a small opening.

Answer 23

Effusion

Question 24

Rates of effusion are proportional to what?

Answer 24

Average speeds

Question 25

At high pressures, the size of particles becomes relatively large compared to the distance between them, which causes what?

Answer 25

Causes them to take up larger volume than predicted

Question 26

At moderate pressure, a gas's volume is less than expected because of what?

Answer 26

intermolecular attraction

Question 27

The closer a gas is to its ____________ ________, the less ideally it acts.

Answer 27

boiling point

Question 28

What equation corrects for real gas behavior?

Answer 28

van der Waals equation