# When magnesium ribbon is added to dilute hydrochloric acid, a vigorous reaction occurs. Describe the energy change that takes place during this reaction, and explain how the breaking and forming of chemical bonds accounts for this energy change.

> Cambridge International IGCSE Chemistry (0620) — 5.1 Exothermic and endothermic reactions · Describe and Explain · 4 marks

## Mark scheme (4 marks)

1. The reaction is exothermic
2. Energy is required / absorbed to break bonds (in the reactants)
3. Energy is released when new bonds form (in the products)
4. More energy is released in bond forming than is absorbed in bond breaking, resulting in a net release of energy

## Key terms

- [energy](https://www.gradenine.co.uk/glossary/energy)

## Related

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- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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