## Lecture 19: Second Law of Thermodynamics and Entropy

November 2, 2017

• Study: Boxes on pp. 166, 168, 169; Ex 1; Eq 9.4; Ex 2; Fig 9.3; boxes on pp. 174, 175; Eqs 9.7, 9.8; Fig 9.5; Eq 9.11; Ex 3.

### Objectives

• (Continuing objective) Be able to relate concepts of thermodynamics and statistical mechanics to “everyday” situations and to discuss various applications of the concepts to practical problems in various fields of science, medicine and engineering.
• State and use the definitions of microstates, macrostates, and multiplicity. Understand the connection between multiplicity and probability.
• Calculate the multiplicity of an Einstein solid or two coupled Einstein solids. Determine the temperature of an Einstein solid.
• Understand the implications of the second law of thermodynamics to heat flow and irreversibility. Describe the second law in terms of probability, multiplicity, and entropy.
• State the definition of temperature and show that this definition is consistent with the Clausius statement of the second law.

### Homework

• Friday's Assigned Problems: Supp CH 9: 1, 2, 3, 4, 5, 6, 7, 8, 14, 16, 18
• Monday's Hand-In Problems: Supp CH 8: 5, 6, 12, 14, 16; Supp CH 9: 10, 11, 12, 13, 15, 17

### Videos of example problems

To see the problem statement, click on the link below. To play the video example, click on the underlined words "Video Demonstration" near the top of the page with the problem statement.
• Video Example #1: Counting the microstates to determine the multiplicity of an Einstein solid. ans: 10
• Video Example #2: Determining the direction of energy flow for two coupled systems. ans: (a) B to A, (b) TB = 400 K, TA = 200 K.

### Pre-Class Entertainment

• Pulled Up, by the Talking Heads
• Peggy Sue, by Buddy Holly
• Pumped Up Kicks, by Foster the People
• Peaches, by Presidents of the United States
• Particle Man, by They Might Be Giants
• Private Idaho, by the B-52s