© 2010 Pearson Education, Inc. Lecture Outline Chapter 10 College Physics, 7 th Edition Wilson / Buffa / Lou

Chapter 10 Temperature and Kinetic Theory © 2010 Pearson Education, Inc.

Units of Chapter 10 Temperature and Heat The Celsius and Fahrenheit Temperature Scales Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale Thermal Expansion The Kinetic Theory of Gases Kinetic Theory, Diatomic Gases, and the Equipartition Theorem © 2010 Pearson Education, Inc.

10.1 Temperature and Heat Temperature is…. Heat is ….. [There are misconceptions in using the terms heat and temperature synonymously] Once energy is transferred, the energy becomes part of the total energy of the molecules of the object or system, that is, its internal energy. © 2010 Pearson Education, Inc.

10.1 Temperature and Heat © 2010 Pearson Education, Inc.

10.1 Temperature and Heat A higher temperature does not necessarily mean that one object has more internal energy than another; the size of the object matters as well. [Mass matters] When heat is transferred from one object to another, they are said to be in thermal contact. Thermal equilibrium: © 2010 Pearson Education, Inc.

10.2 The Celsius and Fahrenheit Temperature Scales A thermometer is used to measure temperature; it must take advantage of some property that depends on temperature. A common one is thermal expansion. © 2010 Pearson Education, Inc.

10.2 The Celsius and Fahrenheit Temperature Scales In everyday use, temperature is measured in the Fahrenheit or Celsius scale. To convert from one to the other: © 2010 Pearson Education, Inc.

10.2 The Celsius and Fahrenheit Temperature Scales What are 20 degrees Celsius and -15 degrees Celsius on the Fahrenheit scale? What are -10 degrees Fahrenheit and 98.6 degrees Fahrenheit on the Celsius scale?

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale When the temperature of an ideal gas is held constant, This is called Boyle’s Law. When the pressure is held constant, This is called Charles’ Law. © 2010 Pearson Education, Inc.

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale Combining gives the ideal gas law: or with Boltzmann’s constant: N is the total number of molecules in the gas. © 2010 Pearson Education, Inc.

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale The ideal gas law can also be written where n is the number of moles of gas and R is the universal gas constant: A mole of a substance contains Avogadro’s number of molecules: © 2010 Pearson Education, Inc.

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale Converting grams to moles. (molar mass) Reviewing: a. 410 grams of Oxygen b. 245 grams of CO 2 c. 138 grams of Nitrogen d. 40 grams of Water

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale If volume is held constant, then P and T are proportional. As T increases, P does what??

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale The temperature at which there is no atomic movement is called absolute zero—no lower temperature is possible. 0 Kelvin Has this ever been achieved??? The Kelvin temperature scale has the same increments as the Celsius scale, but has its zero at absolute zero. © 2010 Pearson Education, Inc.

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale The three temperature scales are shown here. In physics calculations, the Kelvin temperature scale is used. The Kelvin scale is also called the absolute scale, as the Kelvin temperature is proportional to the internal energy. © 2010 Pearson Education, Inc.

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale What is the absolute zero on the Fahrenheit scale?

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale A quantity of ideal gas in a rigid container is initially at room temperature (20 degrees Celsius) and a particular pressure (p 1 ). If the gas is heated to a temperature of 60 degrees Celsius, by what factor does the pressure change?

10.3 Gas Laws, Absolute Temperature, and the Kelvin Temperature Scale A patient receiving breathing therapy purchased a filled M9 oxygen tank. The tank has a volume of 2.5 L and is filled with pure oxygen to an absolute pressure of 100 atm at 20 degrees Celsius. What is the mass of the oxygen in the tank?

10.4 Thermal Expansion Most materials expand when heated. For small changes in temperature, the change in length is proportional to the change in temperature. © 2010 Pearson Education, Inc. Linear Expansion

10.4 Thermal Expansion The changes in area and in volume can be derived from the change in length. © 2010 Pearson Education, Inc. Area Expansion Volume Expansion

10.4 Thermal Expansion A steel beam is 5.0 m long at a temperature of 20 degrees Celsius. On a hot day, the temperature rises to 40 degrees Celsius. What is the change in the beam’s length due to thermal expansion?

10.4 Thermal Expansion A circular piece is cut from a flat metal sheet. If the sheet is then heated in an oven, the size of the hole will become: –Larger –Smaller –Remain Unchanged

10.4 Thermal Expansion A man’s gold wedding ring has an inner diameter of 2.4 cm at 20 degrees Celsius. If the ring is dropped into boiling water, what will be the change in the inner diameter of the ring?

10.4 Thermal Expansion Water behaves nonlinearly near its freezing point—it actually expands as it cools. It’s an unusual property of expanding on freezing and being less dense as a solid than as a liquid. This is why ice floats, and why frozen containers may burst. © 2010 Pearson Education, Inc.

10.5 Kinetic Theory of Gases According to the kinetic theory of gases, pressure is due to elastic collisions of molecules with container walls. There are assumptions of the kinetic theory of gases, and they are??? © 2010 Pearson Education, Inc.

10.5 Kinetic Theory of Gases Using the kinetic theory, it can be shown that Temperature and Kinetic Energy are related. More specifically as Temp. increases, KE ____ The mass and speed are those of an individual molecule. © 2010 Pearson Education, Inc. v rms = √3k b T m

10.5 Kinetic Theory of Gases A helium molecule (He) in a helium balloon is at 20 degrees Celsius. If it is heated to 40 degrees Celsius, its rms speed will –Double –Increase by a factor less than 2 –Be Half as much –Decrease by less than a factor of 2 Calculate the rms speed if the mass is 6.65 x kg.

10.5 Kinetic Theory of Gases The kinetic theory of gases also helps us understand diffusion as a result of the motion of molecules. © 2010 Pearson Education, Inc.