Paper 3 H - SAMPLE SET 1 Q1
1) The rate of chemical reactions can be changed by changing the conditions.
1.1) Methane burns in oxygen to produce carbon dioxide and water.
The activation energy for the reaction is 2648 kJ/mol.
The reaction gives out 818 kJ/mol of energy.
Figure 1 shows the reaction profile for this reaction.
Complete the reaction profile.
Draw arrows to represent:
1.2) What percentage of the activation energy is the energy given out? [1 mark]
1.3) Calcium carbonate decomposes when it is heated:
The decomposition of calcium carbonate is an endothermic reaction.
How would the reaction profile for decomposition of calcium carbonate be different from the reaction profile of methane burning in oxygen? [1 mark]
1.4) Catalysts are used in chemical reactions in industry.
Give two properties of catalysts.
For each property, explain why it makes the catalyst useful in industry. [4 marks]
1.5) Enzymes are biological catalysts.
What type of molecule is an enzyme? [1 mark]
Tick one box.
1.7) If enzymes are denatured they stop working.
Give two ways an enzyme can be denatured. [2 marks]
1. ______________________________________________
2. ______________________________________________
1.7) An enzyme called lactase catalyses the reaction that breaks down lactose to smaller molecules.
One model used to explain how enzymes affect reactions is called the lock and key model.
Use the lock and key model to explain why lactase cannot be used to speed up all chemical reactions. [3 marks]
(Total for Question 1 = 16 marks)
1.1) Methane burns in oxygen to produce carbon dioxide and water.
The activation energy for the reaction is 2648 kJ/mol.
The reaction gives out 818 kJ/mol of energy.
Figure 1 shows the reaction profile for this reaction.
Complete the reaction profile.
Draw arrows to represent:
- the activation energy
- the energy given out.
1.2) What percentage of the activation energy is the energy given out? [1 mark]
1.3) Calcium carbonate decomposes when it is heated:
The decomposition of calcium carbonate is an endothermic reaction.
How would the reaction profile for decomposition of calcium carbonate be different from the reaction profile of methane burning in oxygen? [1 mark]
1.4) Catalysts are used in chemical reactions in industry.
Give two properties of catalysts.
For each property, explain why it makes the catalyst useful in industry. [4 marks]
1.5) Enzymes are biological catalysts.
What type of molecule is an enzyme? [1 mark]
Tick one box.
1.7) If enzymes are denatured they stop working.
Give two ways an enzyme can be denatured. [2 marks]
1. ______________________________________________
2. ______________________________________________
1.7) An enzyme called lactase catalyses the reaction that breaks down lactose to smaller molecules.
One model used to explain how enzymes affect reactions is called the lock and key model.
Use the lock and key model to explain why lactase cannot be used to speed up all chemical reactions. [3 marks]
(Total for Question 1 = 16 marks)