Ch 11

Question 1

Kinetic Molecular Theory

Answer 1

Theory developed to explain physical behavior of the three states of matter (solid, liquid, and gas)

Theory of moving molecules

Question 2

Assumptions of KMT

Answer 2

Matter is composed of tiny particles (atoms, molecules or ions) that have definite and characteristic sizes that do not change.

The particles are in constant, random motions and therefore possess kinetic energy (energy of motion).

The particles interact with one another through attractions and repulsions and therefore possess potential energy.

The velocity of the particles (and their kinetic energy) increases as the temperature is increased.

The particles in a system transfer energy to each other through elastic collisions.

Question 3

Gaseous State

Answer 3

Characterized by dominance of kinetic energy over potential energy
Gas particles have enough kinetic energy to move far apart from each other (moving in straight lines)

There is very little attraction between particles

Question 4

Consequences of the Gaseous State

Answer 4

Indefinite volume and indefinite shape

Low density

Large compressibility

Moderate Thermal Expansion

Question 5

Four Important Gas Variables

Answer 5

1. n = number of moles
2. T = temperature; must be in Kelvin!
3. V = Volume, usually measured in Liters
4. P = Pressure = force/area

Question 6

Relationship Between Pressure and Volume (Boyle’s Law)

Answer 6

When the pressure is increased on a gas, its volume goes down.

PV = constant (T fixed)

Useful form: P1V1 = P2V2

Question 7

Relationship Between Temperature and Volume (Charles’ Law)

Answer 7

When the temperature (K) is increased on a gas, its volume goes up by a constant: V/T = constant (P fixed)
useful form: V1/T1 = V2/T2

Question 8

Relationship between Temperature and Pressure (Gay-Lussac’s Law)

Answer 8

When the temperature (K) is increased on a gas, its pressure goes up as a constant: P/T = constant (V fixed)

Useful form: P1/T1 = P2/T2

Question 9

In Avogadro’s Law:

Answer 9

The volume of a gas is directly related to the number of moles of gas
T and P are constant
V1/n1 = V2 /n2

Question 10

Important Simple Gas Relationships

Answer 10

Boyles Law P1V1 = P2V2 (T fixed)

Charles Law V1/T1 = V2/T2 (P fixed)

Gay-Lussacs P1/T1 = P2/T2 (V fixed)

Avogadros Law V1/n1 = V2/n2 (T&P fixed)

Question 11

STP - Standard Temperature and Pressure (Gases)

Answer 11

T = 273 K (0 oC)
P = 1 atm (760 mmHg)

1 mole of a gas at STP = 22.4L

Question 12

STP

Answer 12

The volumes of gases can be compared when they have the same conditions of temperature and pressure (STP, Standard Temperature and Pressure).

Question 13

Combined Gas Laws

Answer 13

Relates the changes in pressure, volume and temperature, and quantity change of a gas

Question 14

The Ideal Gas Law

Answer 14

Describes the relationships among the four variables for gaseous substances: P, T, V, n

PV = nRT

R is called the ideal gas constant

0.0821 atm·L/mol·K

Question 15

At standard temperature and pressure (STP), 1 mol of a gas occupies a volume of 22.4 L, which is called its

Answer 15

molar volume.

Question 16

The molar volume at STP can be used to form conversion factors.

Answer 16

22.4 L/1mol

Question 17

Density of a Gas at STP

Answer 17

Density= Molar mass/Molar volume (g/L)

Question 18

Ideal Gas Law - expanded

Answer 18

PV = nRT	;    n =  grams/Molar Mass 
n =  g/MM
PV  =  gRT/MM

Question 19

The volume or amount of a gas in a chemical reaction can be calculated from:

Answer 19

STP conditions or the Ideal Gas Law

Mole factors from the balanced equation

Question 20

Dalton’s Law of Partial Pressures

Answer 20

Since gas molecules are so far apart, we can assume they behave independently.

Dalton’s Law: in a gas mixture the total pressure is given by the sum of partial pressures of each component:
Ptotal = P1 +P2+P3+…

Question 21

Partial Pressure

Answer 21

The pressure that a gas in a mixture of gases would exert if it were present alone under the same conditions

Question 22

A gas produced in the Laboratory

Answer 22

Usually contains water vapor

Question 23

The partial pressure of a gas collected over water is obtained by

Answer 23

subtracting the vapor pressure of water.