Counting Equilibrium and Le Chatelier’s Principle (HS)
Equilibrium is a key principle in chemistry, biology, physics and a host of other disciplines. When a system is at equilibrium, no change in the state of the system occurs unless an external force is applied. Two types of
equilibrium exist in nature, static and dynamic. In a static equilibrium, no change occurs to a system over time because all forces acting on the system cancel. In a dynamic equilibrium, the system is continually changing, but each of these changes cancel, leaving the system in the same state. Almost all equilibria in chemistry and biology are dynamic.
objectives
• Students will be able to define the scientific terms system, surroundings, and equilibrium.
• Students will be able to describe the difference between a static and dynamic equilibrium and identify
examples of each of these types of equilibria.
• Students will be able to predict how external forces will affect systems at equilibrium.
Topic(s)
Chemistry and Biology
type
High school lesson
9-12
Grade(s):
time needed
23-30 minutes per lesson
author
Alex Parent, LeAnn Heid
national next gen standards
• MS-LS2-4. Construct an argument supported by empirical evidence that changes to physical or biological
components of an ecosystem affect populations.
• HS-PS1-6. Refine the design of a chemical system by specifying a change in conditions that would produce
increased amounts of products at equilibrium.
• HS-ESS3-3. Create a computational simulation to illustrate the relationships among the management of
natural resources, the sustainability of human populations, and biodiversity.
north dakota standards
• MS-LS2-4. Construct an argument supported by empirical evidence that changes to physical or biological
components of an ecosystem affect populations.
• HS-PS1-6. Refine the design of a chemical system by specifying a change in conditions that would produce
increased amounts of products at equilibrium.
• HS-ESS3-3. Create a computational simulation to illustrate the relationships among the management of
natural resources, the sustainability of human populations, and biodiversity.