Mendeleev · Science

Le Chatelier's principle: reasoning beyond a recipe

Le Chatelier's principle helps qualitatively predict how an equilibrium system responds to certain disturbances. It does not replace the equilibrium expression or calculation when precise values are needed.

Understand before calculating

Le Chatelier's principle helps qualitatively predict how an equilibrium system responds to certain disturbances. It does not replace the equilibrium expression or calculation when precise values are needed.

Example

Adding a reactant can shift composition toward more products, but K itself does not change if temperature stays the same.

The classic trap

Do not turn a model into a literal photograph of reality. Scientific models select particular properties to explain or predict a phenomenon; knowing their limits is part of using them correctly.

Understanding check

Explain the concept to someone who knows the periodic table but not this chapter. Then give one example and one situation where the most common shortcut would become misleading.

Adding a reactant can shift composition toward more products, but K itself does not change if temperature stays the same.