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Using a Model to Describe Gases
While the most useful of the gas laws is the ideal gas equation, under certain conditions, gases do not obey the ideal gas equation. In particular, at high pressures and/or low temperatures, the properties of gases can deviate significantly from the predictions of the ideal gas equation. This topic begins to address what the characteristics of the individual gas particles are that influence a gas to behave as it does.
Lesson 1 (or “Day 1”) Material
Lesson 2 (or “Day 2”) Material
- Day 2 Instructor Presentation
- Day 2 Student Handout
- Day 2 Rubric
- Read Chem 37 – Kinetic Molecular Theory
- Read Chem 37 – Pressure Volume Amount
- Read Chem 37 – Rarefied Gases
Lesson 3 (or “Day 3”) Material
Lesson 4 (or “Day 4”) Material
The Ideal Gas Law: Crash Course Chemistry #12 (12 mins)
Explaining Gas Laws (10 mins)
5 Ideal Gas Law Experiments – PV=nRT or PV=NkT (11:20)
Compare Contrast and Debate
Kickoff Debate Background: xx
Scientist use models to try to understand and predict behaviors in the world. These models can be broadly classified into two types:
- empirical
- physical
An empirical model is one that simply seeks to provide a mathematical relationship between different properties based solely on observation. The combined gas law is an example of an empirical model that is a relationship between the properties of volume, temperature, and pressure for a gas. Based on the combined gas law a chemist could predict the pressure of a known amount of gas given its volume and temperature. A physical model is different in that it seeks to not only predict but to provide some physical insight. The Kinetic Molecular Theory is an example of a physical model. (University of Texas)
- Position A: Empirical models are significantly more useful and interesting.
- Position B: Physical models are significantly more useful and interesting.
Resources Documents and Links
- Chemistry 37 reference sheet (Quick reference, gas law formulas)
Instructor Emphasis:
- Science & Engineering Practice: Analyze and interpret data.
- Cross-Cutting Concept: Systems and System Models.
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