#AP Chemistry: Energy in Reactions - Your Ultimate Study Guide 🚀

Hey there, future AP Chem master! Let's dive into the exciting world of reaction energies. This guide is designed to be your go-to resource, especially the night before the exam. We'll break down complex topics into easy-to-digest pieces, ensuring you feel confident and ready to ace that test! Let's get started!

#⚛️ Review: The Collision Model

Remember, for a reaction to happen, molecules need to collide with:

Sufficient energy
Correct orientation

Key Concept

This guide focuses on the energy aspect of reactions. If you need a refresher on the collision model, check out our previous guide.

#⚡ Energy in Reactions

#What are Elementary Reactions?

An elementary reaction is a single-step reaction involving one or a few molecules. Think of them as the basic building blocks of more complex reactions. They can be:

First-order: Rate depends on one reactant.
Second-order: Rate depends on two reactants.

Quick Fact

Elementary reactions involve bond breaking and bond formation, which directly relate to energy changes.

#Endothermic vs. Exothermic Reactions

Reactions either absorb or release energy. We visualize this using potential energy diagrams (reaction coordinate diagrams).

#Potential Energy Diagrams

*Image Courtesy of Labster Theory*

Endothermic Reactions:
- Reactants have lower potential energy than products.
- Energy is absorbed from the surroundings.
- Think: Reactants + Energy → Products
- The potential energy of the products is higher than the reactants.
Exothermic Reactions:
- Reacta...

Reaction Energy Profile