Physical chemistry is concerned with the gray area that lies between physics (the study of energy) and chemistry (the study of matter). As such, physical chemistry is all about how energy can be stored through, extracted from, and used to drive chemical reactions and chemical systems. A major topic that focuses on how energy and matter interact and affect one another is thermodynamics. But before diving into thermodynamics, it is important to set down a few definitions that make it possible to begin slicing up the topic. 2.1: The System and the Surroundings The Zeroth Law of Thermodynamics deals with the temperature of a system. And while it may seem intuitive as to what terms like “temperature” and “system” mean, it is important to define these terms. The easiest terms to define are the ones used to describe the system of interest and the surroundings, both of which are subsets of the universe. 2.2: Pressure and Molar Volume Italian physicist Evangelista Torricelli (1608 – 1647) (Evangelista Torricelli) was the inventor of an ingenious device that could be used to measure air pressure 2.3: Temperature Another important variable that describes the state of a system it the system’s temperature. Like pressure, temperature scales experienced an important process of development over time. Three of the most important temperature scales in US culture are the Fahrenheit, Celsius, and Kelvin scales. 2.4: The Zeroth Law of Thermodynamics How does one use or measure temperature? Fortunately, there is a simple and intuitive relationship which can be used to design a thermometer – a device to be used to measure temperature and temperature changes. The zeroth law of thermodynamics can be stated as follows: If a system A is in thermal equilibrium with a system B, which is also in thermal equilibrium with system C, then systems A and C share a property called temperature. 2.5: Work and Energy Temperature, pressure and volume are important variables in the description of physical systems. They will also be important to describe how energy flows from one system to another. Generally, energy can flow in two important forms: 1) work and 2) heat. The bookkeeping needed to track the flow of energy is what the subject of Thermodynamics is all about. 2.6: Heat, Heat Capacity, and Energy 2.7: Temperature vs. Heat - What's the difference? 2.E: The Basics (Exercises) Exercises for Chapter1 "The Basics" in Fleming's Physical Chemistry Textmap. 2.S: The Basics (Summary) Summary for Chapter 2 "The Basics" in Fleming's Physical Chemistry Textmap. Thumbnail: Frying an egg is an example of a chemical change induced by the addition of thermal enegy (via heat). Image used iwth permission (CC BY-SA 3.0; Managementboy).