© 2010 Pearson Education, Inc.

PowerPoint® Lectures for College Physics: A Strategic Approach, Second Edition

Chapter 12

Thermal Properties of Matter

© 2010 Pearson Education, Inc. Slide 12-3

© 2010 Pearson Education, Inc. Slide 12-4

© 2010 Pearson Education, Inc. Slide 12-5

© 2010 Pearson Education, Inc.

Phases of Matter

Slide 12-16

© 2010 Pearson Education, Inc.

Atomic mass unit (either u or amu) 1 u = 1.66 X 10^-27 kg

© 2010 Pearson Education, Inc.

Checking Understanding What is the mass, in u, of a molecule of carbon dioxide, CO2?

A.  12 B.  24 C.  32 D.  36 E.  44

Slide 12-12

© 2010 Pearson Education, Inc.

Answer What is the mass, in u, of a molecule of carbon dioxide, CO2?

A.  12 B.  24 C.  32 D.  36 E.  44

Slide 12-13

© 2010 Pearson Education, Inc.

Rank the following in terms of the number of moles, from greatest number of moles to least:

1. 20 g of He (A = 4) 2. 60 g of Ne (A = 20) 3. 120 g of O2 (atomic oxygen, O, has A = 16) 4. 160 g of Ar (A = 40) 5. 200 g of Pb (A = 207)

A.  5 > 4 > 3 > 2 > 1 B.  5 > 4 > 2 > 3 > 1 C.  3 > 1 > 4 > 2 > 5 D.  1 > 4 > 3 > 2 > 5

Checking Understanding

Slide 12-14

© 2010 Pearson Education, Inc.

Answer Rank the following in terms of the number of moles, from greatest number of moles to least:

1. 20 g of He (A = 4) 2. 60 g of Ne (A = 20) 3. 120 g of O2 (atomic oxygen, O, has A = 16) 4. 160 g of Ar (A = 40) 5. 200 g of Pb (A = 207)

A.  5 > 4 > 3 > 2 > 1 B.  5 > 4 > 2 > 3 > 1 C.  3 > 1 > 4 > 2 > 5 D.  1 > 4 > 3 > 2 > 5

Slide 12-15

© 2010 Pearson Education, Inc.

Speed and Kinetic Energy of Gas Molecules

Slide 12-17

© 2010 Pearson Education, Inc.

Checking Understanding An object moving faster than the earth’s escape velocity (about 11 km/s) has enough energy to escape the pull of the earth’s gravity. 11 km/s is pretty speedy, but gas atoms move at high speeds. Which one of the following gas molecules would be most likely to be moving at a speed high enough to escape the earth’s atmosphere?

A.  Carbon dioxide B.  Oxygen C.  Nitrogen D.  Water vapor E.  Hydrogen

Slide 12-19

© 2010 Pearson Education, Inc.

Answer An object moving faster than the earth’s escape velocity (about 11 km/s) has enough energy to escape the pull of the earth’s gravity. 11 km/s is pretty speedy, but gas atoms move at high speeds. Which one of the following gas molecules would be most likely to be moving at a speed high enough to escape the earth’s atmosphere?

A.  Carbon dioxide B.  Oxygen C.  Nitrogen D.  Water vapor E.  Hydrogen

Slide 12-20

© 2010 Pearson Education, Inc.

Example Problem What are the rms speeds of a nitrogen molecule (mass 4.5 × 10-26 kg) at the following temperatures?

A.  Room temperature of 68ºF (20ºC) B.  The coldest temperature ever observed on earth,

-129ºF (-89ºC) C.  Polar night on Mars, -133ºC D.  The coldest temperature achieved in the laboratory,

0.5 nK

Slide 12-18

© 2010 Pearson Education, Inc.

© 2010 Pearson Education, Inc.

The Definition of Pressure

Demo time

1 pascal = 1 Pa = 1 N/m2

1 atmosphere = 101,300 Pa = 101.3 kPa = 14.7 psi

© 2010 Pearson Education, Inc.

© 2010 Pearson Education, Inc.

The Ideal Gas Law Changing the temperature, volume or number of particles changes the pressure of the gas. We can understand this using our model of the ideal gas.

Slide 12-28

© 2010 Pearson Education, Inc.

The Ideal Gas Law

Slide 12-21

© 2010 Pearson Education, Inc.

Ideal Gas Law for a Fixed Amount of Gas

Slide 12-22

© 2010 Pearson Education, Inc.

Reading Quiz 2.  A sample of nitrogen gas is in a sealed container with a

constant volume. Heat is added to the gas. The pressure

A.  increases B.  stays the same C.  decreases D.  can’t be determined with the information given

Slide 12-8

© 2010 Pearson Education, Inc.

Answer 2.  A sample of nitrogen gas is in a sealed container with a

constant volume. Heat is added to the gas. The pressure

A.  increases B.  stays the same C.  decreases D.  can’t be determined with the information given

Slide 12-9