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Year 11 - Science

Factors affecting equilibrium

Industrial chemistry

Unit Summary

This unit covers corrosion, prevention methods, and properties of alloys, ceramics, polymers, and metals. It explores industrial processes like the Haber process, fertiliser production, reaction rates, yields, atom economy, and the trade-offs involving conditions and equilibrium.

Lesson Summary

You will learn to explain how changes in pressure, temperature and concentration, as well as addition of catalysts, affect the equilibrium position of a reversible reaction.

Key Notes

  • Catalysts, pressure, temperature & concentration of solutions can affect equilibrium position of a reversible reaction.
  • If the conditions of a reversible reaction are changed, the equilibrium will move to counteract that change.
  • A catalyst increases the rate at which equilibrium is achieved.
  • Increasing temperature increases the rate of both reactions; equilibrium shifts in favour of the endothermic reaction.
  • Increasing the concentration or pressure of a substance increases the rate of reaction; equilibrium shifts in response.

Vocabulary To Learn

  • Le Chatelier's principle: states that if a dynamic equilibrium is disturbed by changing the conditions, the equilibrium position 'shifts' to counteract the change.
  • dynamic equilibrium: occurs in a closed system when the forward and backward reactions of a reversible chemical reaction occur at the same rate; and the concentrations of reactants and products remain constant.
  • equilibrium position: refers to the relative concentrations of reactants and products in a reversible reaction at equilibrium.
  • reaction rate: is the speed with which a chemical reaction takes place, measured by the amount of a reactant used or amount of product formed in a given time.

Common Mistakes To Avoid

  • At dynamic equilibrium the reactions stop; increasing pressure always shifts equilibrium to one side; increasing temperature always favours product formation; catalysts shift the equilibrium position.

3 Quick Questions (With Answers)

1. Explain the scientific idea in this lesson using two key points.

Catalysts, pressure, temperature & concentration of solutions can affect equilibrium position of a reversible reaction. If the conditions of a reversible reaction are changed, the equilibrium will move to counteract that change.

2. Define this scientific word and use it in context. 'Le Chatelier's principle'

states that if a dynamic equilibrium is disturbed by changing the conditions, the equilibrium position 'shifts' to counteract the change. Include the word in a full scientific explanation, not as a single label.

3. Correct this common scientific misunderstanding.

Mistake: At dynamic equilibrium the reactions stop; increasing pressure always shifts equilibrium to one side; increasing temperature always favours product formation; catalysts shift the equilibrium position. Correction: At dynamic equilibrium, reactions continue at equal rates. Pressure shifts equilibrium only if gas molecule numbers differ. Temperature favours the endothermic direction when increased. Catalysts speed up reaching equilibrium but don't shift it.

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