A theory is the more impressive the greater the simplicity of its premises, the more diverse the things it relates, and
the more extended its area of applicability. Therefore the deep impression which classical thermodynamics made
upon me. It is the only physical theory of universal content which, I am convinced, . . . will never be
- Albert Einstein
So far, we have been looking at chemistry from a microscopic scale upwards, starting with the electron, proton,
and neutron, and working our way up to the molecules. In this fashion we learned to understand and predict
what happens on a macroscopic scale. In thermodynamics we will look at matter from the another point of view.
We will consider only the macroscopic properties of matter. Thermodynamics is a unique theory because it looks
only at the macroscopic properties of matter and, on that basis alone, tries to predict what other macroscopic
behavior exists. (
, whether a particular reaction will occur or not occur under certain conditions). It is based
on a few basic tenets and is a general theory. In fact, if the entire atomic theory of matter were overthrown (
electrons, neutrons, protons, atoms, molecules), the foundations of thermodynamics would still be sound. There
are many things, however, that thermodynamics doesn't tell us. For example, while thermodynamics tells us that
diamonds at atmospheric pressure will transform into graphite, it doesn't tell us how long for that
transformation to occur.
To best understand the application of thermodynamics to chemistry we will first review some important general
concepts. Scientists like to divide or cut the whole universe into smaller parts, and then study (and hopefully
understand) the smaller parts. In the science of thermodynamics things are no different and we begin by
distinguishing between our system of interest and its surroundings.
System: The part of the universe under study.
Surroundings: Everything else that can interact with the system.
In chemistry, the system is often the reactants and products of the chemical reaction, and surroundings will be
some kind of container and everything outside the container. The surroundings may even include a solvent in
which the reactants and products are dissolved.
Associated with a system are intensive and extensive properties.