Overview
Students will be guided through modeling a full chemical reaction by counting the number of bonds that must be broken versus the number of bonds formed in order to determine if the overall reaction is likely endothermic or exothermic. Individual bond breaking and bond making steps will be included in the model as well as the PE/KE of the system/surroundings throughout the reaction.
Standards
Next Generation Science Standards
- Physical Science
- [HS-PS1-4] Develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy.
- [HS-PS3-2] Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles (objects) and energy associated with the relative positions of particles (objects)
Computational Thinking in STEM
- Data Practices
- Collecting Data
- Creating Data
- Manipulating Data
- Visualizing Data
- Analyzing Data
- Modeling and Simulation Practices
- Assessing Computational Models
- Using Computational Models to Understand a Concept
- Systems Thinking Practices
- Communicating Information about a System
- Investigating a Complex System as a Whole
- Thinking in Levels
- Understanding the Relationships within a System
Activities
- 1. Modeling A Chemical Reaction
Student Directions and Resources
The Law of Conservation of Energy states that energy is neither created nor destroyed in any chemical reaction. Thus, we can determine if a chemical reaction is endothermic or exothermic by quantifying both the amount of energy transferred from the surroundings into the system to break bonds, and the amount of energy released from the system back into the surroundings when bonds are formed.
You will need the following resources to complete this assignment.
1. Modeling A Chemical Reaction
Your instructor will begin by modeling an endothermic chemical reaction on the board for you using a set amount of energy (potential energy + kinetic energy) that will be traced from the surroundings into the system and back out again. The amount of energy absorbed or released will be based on the number of bonds that are broken versus the number of new bonds formed in the chemical reaction.
After your instructor models the endothermic reaction, you will model an exothermic reaction on your handout using the same principles and ideas demonstrated in your instructor's model on the board. Then you will practice modeling two more chemical reactions; you will need to determine if these reactions are endothermic or exothermic during the modeling process to ensure the correct amount of energy absorbed or transferred throughout the chemical reaction
