How does a catalyst work?
3 marks · EasyDescribe the energy change from reactants to products in an exothermic reaction profile diagram.
On a reaction profile diagram, where is the activation energy shown?
Explain how adding a catalyst would change the appearance of the reaction profile diagram.
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(a) The products have lower energy than the reactants.
(b) It is the energy difference from reactants up to the top of the curve.
(c) The peak is lower; the activation energy is shown as smaller.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States that the products have lower energy than the reactants / energy decreases from reactants to products.
B1 (b) · 1 mark · Identifies activation energy as the energy rise from reactants to top of the curve.
B1 (c) · 1 mark · Explains that the addition of a catalyst lowers the peak (activation energy) in the diagram.
Worked solution
(a) The products are at a lower energy level than the reactants in an exothermic reaction.
(b) The activation energy is represented by the energy difference from the reactants level up to the top of the curve (the peak).
(c) Adding a catalyst provides a lower peak, showing a new lower activation energy pathway.