Module 8: Thermochemistry

Think about the last time you took a bath. Over time, the water becomes warm and then cool. Did you ever wonder why the water became cold? Or, where the heat from the bath goes? The answers are found in thermochemistry. Thermochemistry is also known as chemical thermodynamics. During this module, you will investigate how heat and energy relate to one another within a chemical reaction. In addition, you will explore concepts such as heat changes associated with chemical reactions, catalysts, activation energy, reaction profiles, entropy, thermostoichiometry, free energy, phase change calculations, specific heat capacity, and calorimetry. Once you have completed this study, you will know why your bath cools and where its energy goes.

Getting Started

Your investigation of thermochemistry begins by exploring heat changes associated with chemical reactions. In this study, you will learn about the system, surroundings, and if a reaction is exothermic or endothermic. To get started, think about the following scenario and try and come up with answers to the questions. In this scenario, a candle is burning in a dark room.

• Can you describe the system?
• Can you describe the surroundings?
• Which has more heat the system or the surroundings?
• Is heat flowing into or out of the system?

 

Key Vocabulary

To view the definitions for these key vocabulary terms, visit the course glossary.

activation energy	enzyme	molar heat of fusion
calorie	exothermic	molar heat of vaporization
calorimeter	free energy	specific heat capacity
calorimetry	freezing	stoichiometry
catalyst	heat capacity	sublimation
condensation	Hess’s Law	surroundings
deposition	heterogeneous catalyst	system
endothermic	homogeneous catalyst	vaporization
enthalpy	melting
entropy	molar heat of condensation