Why study/care about thermodynamics?
From physics, you have learned that every object has a certain amount of energy, and that energy can be split into kinetic and potential energy. Mechanics typically deals with discrete (separate) objects. It provides ways to quantify, for example, the object’s movement, direction, and energy. Using this same approach to study chemical phenomena is typically very complex because (1) a large number of objects (i.e. molecules) are involved and (2) each molecule has a different amount of energy. During a chemical reaction, we must also consider that some of these molecules are changing as reactants transform into products. Physical chemistry provides tools to address each of these challenges. The concepts in Part 1 will help you describe chemical energy and the concepts in Part 2 will help you describe how quickly chemical reactions occur.
There are different ways to treat systems with a large number of molecules. This course will begin with thermodynamics, which focuses on the bulk (i.e. macroscopic) properties of matter. In essence, thermodynamics focuses on the nature of heat and its conversion to/from mechanical energy and chemical energy. In other words, thermodynamics is the study of the properties of matter and how energy is stored and transferred on a macroscopic scale. One of the features of thermodynamics is that it is primarily independent of atomic-level structure, so the results of thermodynamic studies can be generalized across all kinds of chemical compounds. Another way to treat systems with a large number of molecules is to examine their energy using a statistical treatment called statistical mechanics. While the course will not focus on statistical mechanics, it will be used to help understand non-intuitive concepts.
Thermodynamics begins with the assumptions that (1) the thermodynamic universe contains all energy and matter (i.e. there is no “outside” this universe) and (2) any fluctuations of energy or matter will be small compared to the scale of the universe. These assumptions limit the kinds of systems we can study. Thermodynamics will not accurately describe systems governed by quantum mechanics (very small), or systems that include the majority of the universe (very large). Between these limits of very small and very large systems, there are many systems we can examine.