Le Chatelier Shift Calculator

Work out le chatelier shift instantly with clear inputs, formula shown and shareable results.

About Le Chatelier Shift Calculator

Le Chatelier's principle becomes quantitative once Q is compared with K. When Q is below K there is a shortage of products and the reaction runs forward; above K it reverses. The size of the drive is RT ln(Q/K), so a Q ten times below K at room temperature corresponds to about -5.7 kJ/mol pushing the reaction forward.

Formulas

Comparison test

Q < K forward, Q > K reverse, Q = K at equilibrium

Free energy drive

dG = RT ln(Q/K)

Worked example

With the default values below, Le Chatelier Shift Calculator returns Q / K of 0.2500. Change any input above and every figure here is recalculated in your browser.

Inputs used

Reaction quotient Qminimum 0: 0.5
Equilibrium constant Kminimum 0: 2
Temperatureminimum 1 K: 298 K

Results

Q / K: 0.2500
Direction Of Shift: Shifts forward, towards the products
Free Energy Drive: -3.435 kJ/mol
log10(Q/K): -0.6021

Step by step

1Values used
2Comparison test
3Free energy drive
4Q / K= 0.2500
5Direction Of Shift= Shifts forward, towards the products
6Free Energy Drive= -3.435 kJ/mol
7log10(Q/K)= -0.6021

Assumptions and limits

The result is derived only from the 3 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 4 decimal places, 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

Does adding a catalyst shift the position?

No. A catalyst speeds both directions equally, so it changes how fast equilibrium is reached but not where it lies.

Why does temperature appear here?

Because the free energy drive scales with RT. The direction depends only on Q versus K, but the energy behind the shift grows with temperature.