Final Notes for Thermodynamics Test: Chapter 11

Read p. 427 REALLY WELL, including the diagrams of the ball.

Read about entropy WELL. Remember that entropy is the amount of disorder. Read the following:

If you walk into the woods and see that all of the trees are in perfect lines you know that someone did this. It was not natural. The universe is not orderly.

In order for things to become more ordered (to decrease entropy) requires OUTSIDE WORK. It is not possible for a system to decrease entropy (become more ordered) by itself. What is outside work? Outside work means work from outside the system.

Examples of outside work:

1. You picking up your room. The room has more entropy (disorder) before you clean it. You are external work to the room.

2. You turning dice so they are all facing the same way. The likelihood of them facing the same direction is VERY unlikely by themselves (closed system). You do external work to order them (decrease the entropy).

SOOOOO - it is impossible for a closed system to decrease its entropy. This is the 2nd Law of Thermodynamics. Decreasing entropy requires external work. An isolated system (closed system) will always gain entropy (disorder).