New
New
Year 11
OCR
Higher

Equilibrium: balance between rate, safety, environment and economics

I can describe how various factors influence the reaction conditions for industrial equilibria, and understand the trade-offs between production rate, equilibrium position, safety, and cost.

New
New
Year 11
OCR
Higher

Equilibrium: balance between rate, safety, environment and economics

I can describe how various factors influence the reaction conditions for industrial equilibria, and understand the trade-offs between production rate, equilibrium position, safety, and cost.

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Lesson details

Key learning points

  1. Industrial equilibria involve a trade-off between production rate and equilibrium position.
  2. Temperature, pressure, surface area, concentration, and catalysts impact rates and equilibrium, often in opposing ways.
  3. High pressures and temperatures boost reaction rates but must balance safety and cost.
  4. High pressures are costly and increase equipment failure risk.
  5. Low temperatures slow reactions but can favour desired product in exothermic reactions.

Keywords

  • Equilibrium position - refers to the relative concentrations of reactants and products in a reversible reaction at equilibrium.

  • Dynamic equilibrium - occurs in a closed system when the forward and reverse reactions of a reversible chemical reaction are occurring at the same rate; and the concentrations of reactants and products remain constant.

  • 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.

  • Haber process - an industrial method for producing ammonia.

  • Contact process - an industrial method for producing sulfuric acid.

Common misconception

Higher temperature/pressure always increases the yield of products in equilibrium reactions.

High temperature can decrease yield in exothermic reactions by shifting equilibrium toward reactants; high pressures can decrease yield where there are fewer gaseous moles of reactants than products.

Emphasise how different conditions affect both reaction rates and equilibrium positions, using specific examples from the Haber and Contact processes.
Teacher tip

Equipment

None required.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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6 Questions

Q1.
The industrial method for producing ammonia from hydrogen and nitrogen is called the .
Correct Answer: Haber process, haber process
Q2.
What name is given to a substance that increases the rate of a reaction, by providing an alternative reaction pathway?
Correct Answer: catalyst, a catalyst
Q3.
Which of the following chemical reactions are exothermic?
Photosynthesis
Thermal decomposition
Correct answer: Respiration
Correct answer: Combustion
Q4.
In an equation for a chemical reaction, what is the meaning of this symbol ⇌?
Correct Answer: reversible reaction, reversible
Q5.
Which of the following factors does not increase the rate of this chemical reaction? NaOH (aq) + HCl (aq) → H₂O (l) + NaCl (aq)
Increasing the concentration
Increasing the temperature
Correct answer: Increasing the pressure
Q6.
What is normally used as a catalyst in the Haber process?
Correct Answer: iron

6 Questions

Q1.
Match the following terms with the correct definitions.
Correct Answer:Equilibrium position,At equilibrium, the relative concentrations of reactants and products.

At equilibrium, the relative concentrations of reactants and products.

Correct Answer:Dynamic equilibrium,Forward and reverse reactions occur at the same rate.

Forward and reverse reactions occur at the same rate.

Correct Answer:Reaction rate,Speed at which a chemical reaction takes place.

Speed at which a chemical reaction takes place.

Correct Answer:Contact process,Industrial method for producing sulfuric acid.

Industrial method for producing sulfuric acid.

Correct Answer:Haber process,Industrial method for producing ammonia.

Industrial method for producing ammonia.

Q2.
Which of the following factors does not affect the position of equilibrium?
Temperature
Pressure
Correct answer: Catalysts
Concentration
Q3.
What impact would increasing the pressure have on this reversible reaction? 3H₂ (g) + N₂ (g) ⇌ 2NH₃ (g)
Correct answer: The reaction rate would increase.
The reaction rate would decrease.
Correct answer: The yield of ammonia would increase.
The yield of ammonia would decrease.
Q4.
A reversible reaction is exothermic in the forward reaction. Which of the following statements about the reaction are correct?
Correct answer: A high temperature would increase the rate of the reaction.
A high temperature would increase the yield.
Correct answer: A high temperature would decrease the yield.
A high temperature would decrease the rate of reaction.
Q5.
During a reversible reaction the desired product is removed, the pressure and temperature are kept constant. What impact does this have on the reaction?
Correct answer: It decreases the concentration of the desired product (in the reaction mixture).
Correct answer: It shifts the equilibrium position towards the desired product.
It increases the rate of reaction.
It decreases the yield of the desired product.
Q6.
Why is ammonia manufactured at 200 atmospheres rather than the higher 400 atmospheres? 3H₂ (g) + N₂ (g) ⇌ 2NH₃ (g)
Increasing the pressure would decrease the rate of reaction.
Correct answer: Increasing the pressure would increase the cost.
Correct answer: Increasing the pressure would increase the equipment failure risk.
Increasing the pressure would decrease the yield.