Le Chatelier's Principle Examples in Chemistry

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Le Chatelier's Principle.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

When a system at equilibrium is disturbed, it shifts to counteract the disturbance.

Push on equilibrium, and it pushes back. Add something, and the system uses it up.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Systems at equilibrium resist change by shifting to partially counteract whatever was added or removed.

Common stuck point: Catalysts don't shift equilibrium—they just speed up reaching it.

Worked Examples

Example 1

easy
State Le Chatelier's principle and explain what it predicts about equilibrium systems.

Solution

  1. 1
    Le Chatelier's principle states: if a system at equilibrium is subjected to a change (stress), the system will shift to partially counteract that change and establish a new equilibrium.
  2. 2
    Stresses include changes in concentration, pressure, or temperature.
  3. 3
    The system responds by shifting the equilibrium position (favoring either the forward or reverse reaction) to reduce the effect of the disturbance.

Answer

\text{A system at equilibrium shifts to oppose any applied stress.}
Le Chatelier's principle is a qualitative tool for predicting how an equilibrium system responds to changes. It does not tell us the exact new concentrations, but it tells us the direction of the shift.

Example 2

medium
For the exothermic reaction \text{N}_2 + 3\text{H}_2 \rightleftharpoons 2\text{NH}_3 + \text{heat}, predict the effect of: (a) increasing temperature, (b) removing \text{NH}_3, (c) increasing pressure.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

medium
For the equilibrium \text{CaCO}_3\text{(s)} \rightleftharpoons \text{CaO(s)} + \text{CO}_2\text{(g)} (endothermic), predict the effect of increasing temperature on the amount of \text{CO}_2 produced.

Example 2

hard
The contact process produces sulfur trioxide: 2\text{SO}_2\text{(g)} + \text{O}_2\text{(g)} \rightleftharpoons 2\text{SO}_3\text{(g)}, \Delta H = -198\,\text{kJ}. Explain why the industrial process uses: (a) high pressure, (b) moderate temperature (450°\text{C}) rather than low temperature, and (c) a \text{V}_2\text{O}_5 catalyst.
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Related Concepts

Chemical Equilibrium

Background Knowledge

These ideas may be useful before you work through the harder examples.

equilibrium