Wyoming Science HS-PS1-6

ScienceGrades 9–12Physical Science

The Standard

Evaluate the design of a chemical system by changing conditions to produce increased amounts of products at equilibrium, and refine the design, as needed.

2023 Wyoming Science Content and Performance Standards · PS1 Matter and Its Interactions

Teacher's field guide

What This Standard Means

What Students Need to Do: Students change a condition in a reversible reaction to try to increase the amount of product at equilibrium. They use results to judge whether the change worked and revise their plan.
What Mastery Looks Like: A student can predict how a change in temperature, pressure, or concentration will affect a given reaction. They can compare the result with a control and choose a better condition if needed.
Common Misconceptions: Students may think a catalyst increases the final amount of product, rather than helping the reaction reach equilibrium faster. They may assume higher temperature always increases product, even when the reaction releases heat.
How to Assess It: Exit ticket: A student heats N₂ + 3H₂ ⇌ 2NH₃ + heat and gets less ammonia at equilibrium. Name one change that would raise the final amount of ammonia, and explain why.

Lesson moves

Ways to Teach It

Mix dilute iron(III) nitrate and potassium thiocyanate in three tubes; add iron solution to one and thiocyanate solution to another, then compare colors.
Ask: A student adds a catalyst and sees ammonia form faster; does that prove the final amount of ammonia increased?
Give pairs ammonia and sulfur trioxide equation cards marked with heat; have them race to predict the effects of pressure and temperature changes.
Sketch an ammonia plant compressor on the board and ask why engineers might stop increasing pressure despite getting more ammonia.

Free download