Endothermic reactions
2 marks · EasyExplain why energy must be supplied to the reactants in an endothermic reaction. Refer to the relative energies of reactants and products in your answer.
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Energy is needed in an endothermic reaction because the products have more energy than the reactants. This extra energy must be supplied for the reaction to happen.
Common mistakes: not mentioning energy difference between reactants and products
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Marking points
B1 · 1 mark · States that products have more energy than reactants or that energy is taken in.
B2 · 1 mark · Explains this means energy must be supplied to reactants for the reaction to proceed.
Worked solution
In an endothermic reaction, the products have higher energy than the reactants. To reach that higher energy, the system must absorb energy from the surroundings.