Safety boundary
Use virtual equilibrium perturbations and supplied datasets only; no unsupervised color-change chemistry.
Explicit chemistry instruction
A concentration disturbance changes Q immediately while K remains fixed at constant temperature.
The system then evolves in the direction that brings Q back toward K.
Le Châtelier language is a shortcut; Q/K reasoning gives the stronger mechanistic basis.
Vocabulary: stress; concentration; shift; Q; equilibrium position.
Worked example
Adding reactant changes Q immediately and can drive a compensating composition change while K stays fixed.
Guided question
Why does K stay unchanged after a concentration perturbation at constant temperature?
Independent work
- Predict four concentration shifts.
- Explain one with Q/K.
- Separate immediate change from subsequent response.
Misconception check
The system does not 'know' how to oppose stress; rates respond to changed concentrations.
Formative check
What changes immediately after adding reactant: K or Q?
Reveal response
Q changes; K does not at fixed temperature.
Mentor evidence conference
Ask Archaemenes to audit whether Q, K, and rate effects are being kept distinct.
Teacher guidance
Foundation: Use before/after tables.
Core: Predict concentration responses.
Extended: Explain shifts with Q/K.