Le Chatelier’s Principle Simulator
Predict how an equilibrium shifts when you change concentration, temperature, or pressure. Enter a balanced reaction (with phases), choose a stress, and see Left/Right/No shift with clear reasoning.
Background
Le Chatelier’s principle says a system at equilibrium will respond to a disturbance by shifting to partially counteract that change. This simulator uses your balanced equation, phase tags (e.g., H2(g)), and reaction enthalpy (exo/endo) to predict qualitative shifts.
How to use the simulator
1) Type a balanced reaction with phases: e.g., N2(g) + 3 H2(g) ⇌ 2 NH3(g).
2) Choose exothermic or endothermic (overall).
3) Pick a stress (concentration, temperature, pressure/volume, inert gas, or catalyst).
4) Click Predict Shift to see Left/Right/No shift with reasoning.
Notes
- Pressure/volume logic uses Δngas from the (g) tags in your equation.
- Catalysts do not change equilibrium position—only the rate to reach it.
- Pure solids/liquids don’t affect Q; changing their amounts doesn’t shift equilibrium.
Example Problems & Step-by-Step Solutions
Example 1 — Pressure increase
N2(g) + 3 H2(g) ⇌ 2 NH3(g), exothermic. Increase pressure (decrease volume).
- Δngas = (2) − (1 + 3) = −2 (fewer moles on product side).
- Higher pressure favors fewer gas moles → shift right (toward NH3).
Example 2 — Temperature increase
Same reaction, exothermic. Increase temperature.
- Treat heat as a product. Adding heat is like increasing a product.
- System shifts to consume heat → shift left (toward reactants).
Frequently Asked Questions
Q: Does adding an inert gas change equilibrium?
At constant volume: no. At constant pressure: it can shift toward the side with more gas moles.
Q: Do catalysts shift equilibrium?
No. They only help the system reach equilibrium faster.
Q: Do solids and liquids matter?
Pure solids/liquids are omitted from Q; changing their amounts doesn’t shift equilibrium.
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