Why do reactions either give out or absorb heat?
2 marks · NormalExplain what happens to energy during the breaking and making of bonds in a chemical reaction.
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Also accept: Energy is absorbed to break bonds and released when bonds are made.; Breaking bonds takes in energy, making bonds gives out energy.
Common mistakes: Stating that both processes release or absorb energy.
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Marking points
B1 · 1 mark · States that bond breaking requires energy (is endothermic) or absorbs energy.
B2 · 1 mark · States that bond making releases energy (is exothermic) or gives out energy.
Worked solution
During chemical reactions, energy is taken in to break bonds in the reactants. Energy is then released when new bonds are made in the products.