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Unformatted text preview: Chapter 5 Summary Thermochemistry Basic Definitions: The study of energy and its transformations is known as thermodynamics . Thermochemistry is the study of energy changes in chemical reactions involving heat. Energy (E) is the capacity to do work (w) or to transfer heat (q). Potential energy is the energy an object has relative to other objects; it increases with height: = . Ep mgh Kinetic energy is the energy an object has in motion; it increases with velocity: = . Ek mv2 Fundamental Thermochemistry Definitions (EXTRE MELY I M PORTANT): The Joule is the SI unit of measuring energy. Joules can measure both work and heat. The system is the chemical reaction which is occurring (think of a chemical equation). When the system gains heat and work from the surroundings (the surroundings either lose heat or do work on the system), they are always POSIT IVE in any equations. The surroundings are everything else besides the chemical reaction. When the surroundings gain heat and work from the system (the system either loses heat or does work on the surroundings), they are always NEGAT IVE in any equations. Work is the energy used to cause an object to move against a force. Therefore, work is defined as force exerted over a distance: = . w Fd Heat is the energy transferred from a hotter object to a colder one. First Law of Thermodynamics Definition: Energy is neither created nor destroyed. I nternal energy is the sum of all kinetic and potential energy in a system. The change in internal energy is known as . E These are two important equations to memorize for it: =- E Efinal Einitial = + E q w E is also known as a state function . A state function has two important components associated with it that must be memorized: 1. State functions depend ONLY on the final and initial values.State functions depend ONLY on the final and initial values....
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