Le Chatelier’s Principle Flashcards

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What does Le Chatelier’s Principle say about a reaction at equilibrium?

It says that when you change the conditions, the equilibrium shifts to oppose the change.

Name three conditions that can change the position of equilibrium in a reversible reaction.

Temperature, pressure (for gases), and the concentration of reactants or products.

If you increase the concentration of a reactant at equilibrium, what happens?

The equilibrium shifts towards the products, to use up some of the extra reactant.

If you increase the concentration of a product at equilibrium, what happens?

The equilibrium shifts towards the reactants, to use up some of the extra product.

When you increase the temperature of a reaction at equilibrium, which direction is favoured?

The equilibrium shifts in the endothermic direction, which takes in heat.

If the forward reaction is exothermic, how does lowering the temperature affect the yield of products?

Lowering the temperature shifts the equilibrium towards the exothermic forward reaction, so the yield of products increases.

In a reversible reaction involving gases, what happens if you increase the pressure?

The equilibrium shifts to the side with fewer gas molecules, to reduce the pressure.

In a reversible reaction involving gases, what happens if you decrease the pressure?

The equilibrium shifts to the side with more gas molecules, to increase the pressure again.

How does adding a catalyst affect the position of equilibrium?

A catalyst does not change the position of equilibrium; it only helps the system reach equilibrium faster.

What does it mean if we say the equilibrium has ‘shifted to the right’?

It means the reaction now forms more products and fewer reactants than before.

In the Haber process, why does a high pressure increase the yield of ammonia, NH3?

Because there are fewer gas molecules on the ammonia side, higher pressure shifts the equilibrium towards making more ammonia.