A food manufacturer uses a reversible reaction carried out in a closed system to produce a flavouring compound. Explain what is meant by dynamic equilibrium and describe what happens to the position of equilibrium if the concentration of a reactant is increased.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
In the food industry, many flavouring compounds are produced using reversible reactions. These reactions are carried out in closed systems so that equilibrium can be established and the yield of product can be controlled.
Model answer (4 marks)
At dynamic equilibrium the rate of the forward reaction equals the rate of the reverse reaction.
The concentrations of reactants and products remain constant.
If the concentration of a reactant is increased, the equilibrium shifts to the right, towards the products.
More products are formed until the system reaches a new equilibrium again.
The concentrations of reactants and products remain constant.
If the concentration of a reactant is increased, the equilibrium shifts to the right, towards the products.
More products are formed until the system reaches a new equilibrium again.
Examiner tips
- Use the exact phrase "dynamic equilibrium" and state the rate equality first. Mention that concentrations remain constant. Apply Le Chatelier’s principle: increasing a reactant shifts right. Show the result: more products until new equilibrium.
- common_mistakes
- :
- Saying the equilibrium shifts left when a reactant is added. Forgetting to mention that concentrations stay constant. Using vague terms like "more of something" without specifying products.
Mark scheme (4 marks)
- At dynamic equilibrium the rate of the forward reaction is equal to the rate of the backward reaction.
- At dynamic equilibrium the concentrations of reactants and products remain constant.
- If the concentration of a reactant is increased, the position of equilibrium shifts to the right / towards the products.
- More products will be formed until equilibrium is reached again / the change is counteracted.
Key terms in this question
dynamic equilibrium · closed system · reversible reaction · position of equilibrium · concentration
Related
- All OCR GCSE Chemistry A: Gateway Science (J248) revision notes →
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- Decode the mark scheme abbreviations →
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