Le Chatelier Calculator
Predict how an equilibrium shifts when concentration, pressure or temperature changes.
About Le Chatelier Calculator
Le Chatelier’s principle says a system at equilibrium shifts to oppose any imposed change. Pressure only matters when the gas mole count differs between sides, and temperature shifts equilibrium in the endothermic direction when raised. Ammonia synthesis illustrates the classic conflict: high pressure and low temperature both favour yield, but low temperature makes the rate impractically slow.
Formula
Le Chatelier
Increasing pressure favours the side with fewer gas moles; heating favours the endothermic direction
- Δn(gas)
- Moles of gaseous product less gaseous reactant
- exothermic
- Releases heat, so heating drives it backwards
Worked example
With the default values below, Le Chatelier Calculator returns Effect of the Pressure Change of Shifts toward products — fewer gas moles. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Moles of gaseous reactantsaccepts 0–20
- 4
- Moles of gaseous productsaccepts 0–20
- 2
- Enthalpy change of reactionaccepts -1,000–1,000 kJ/mol
- -92 kJ/mol
- Change in pressureaccepts -99–500 %
- 50 %
- Change in temperatureaccepts -500–500 K
- 50 K
Results
- Effect of the Pressure Change
- Shifts toward products — fewer gas moles
- Effect of the Temperature Change
- Shifts toward reactants — heating opposes an exothermic reaction
- Change in Moles of Gas
- -2
- Reaction Type
- Exothermic — releases heat
- Combined Guidance
- High pressure and low temperature both favour products, but low temperature slows the rate
Step by step
- 1Values used
- 2Le Chatelier
- 3Effect of the Pressure Change= Shifts toward products — fewer gas moles
- 4Effect of the Temperature Change= Shifts toward reactants — heating opposes an exothermic reaction
- 5Change in Moles of Gas= -2
- 6Reaction Type= Exothermic — releases heat
- 7Combined Guidance= High pressure and low temperature both favour products, but low temperature slows the rate
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Le Chatelier calculated?
Increasing pressure favours the side with fewer gas moles; heating favours the endothermic direction Le Chatelier’s principle says a system at equilibrium shifts to oppose any imposed change. Pressure only matters when the gas mole count differs between sides, and temperature shifts equilibrium in the endothermic direction when raised.
Why does Le Chatelier matter?
Ammonia synthesis illustrates the classic conflict: high pressure and low temperature both favour yield, but low temperature makes the rate impractically slow.
What values do I need to enter?
This calculator takes 5 inputs: Moles of gaseous reactants, Moles of gaseous products, Enthalpy change of reaction, Change in pressure, Change in temperature. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.