Search

Thermodynamics

What is the difference between chemistry and physics? In a physics course, the study of the phases of matter is a subchapter of the chapter on thermodynamics. Here we will do something of a Sluffover and Passoff job on thermodynamics just to give you a taste of the idea.

The word "thermodynamics" means the "movement of heat." That sounds somewhat silly if you define heat as, "the way we feel the movement of molecules." Perhaps a more useful definition of thermodynamics is, "the flow or transfer of heat." The symbol, "Q" is used for this flow of heat energy.

The First Law of Thermodynamics can be stated something like this: "Heat is a form of energy. Types of energy can be transferred from one type to another, and it is possible to account for all of the energy to show no loss or gain of energy from the transfer." This law is apparently violated by the famous Einstein equation, E = m c2, in which E is energy, m is mass and c is the velocity of light. This is the equation that shows that an incredibly small mass disappears when a nuclear reaction occurs and an incredibly large amount of energy is made. Einstein's equation does not violate the first law, but just shows us the difficult idea that mass and energy are just two different forms of the same thing. Mass is just a very concentrated form of energy. It is pretty difficult to get energy from mass. (And even more difficult to get mass from energy!)

The Second Law of Thermodynamics is a bit more complex. There are several ways to express it and several parts to it. "Usable work from a heat engine is available from a difference in temperature rather than any amount of material at the same temperature." and "When two materials are combined, the temperature of both of them will become the same, a weighted average based on the specific heat and mass of the two materials coming together." There is more to the second law, but these will do for now.

The Third Law of Thermodynamics describes material under a very specialized condition. It shows that it is impossible to bring and keep a material to absolute zero temperature, since absolute zero is the condition wherein a material has absolutely no motion of the atoms or molecules.

If a scientist looks at you without the trace of a smile and talks about the fourth law of thermodynamics, you know to avoid playing poker with that individual. There is no such thing, but in jest many a scientist has talked about Murphy's Law as being a Fourth Law of Thermodynamics, when actually it is a special case of the Second Law. Murphy's Law says, "If anything can go wrong, it will," and other humorous ways to explain perversity. The chemistry corollary to this is that, "All organic reactions tend toward maximum gunk." And, "Buttered toast always lands butter - side - down," is another manifestation of Murphy's Law.

if (isMyPost) { }