# When magnesium ribbon is added to dilute hydrochloric acid, the temperature of the solution rises. Explain what this observation tells us about the type of energy change occurring, and describe how the enthalpy change for this reaction would be represented on a reaction profile.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 3.1 Energetics · Explain · 4 marks

> Magnesium reacts with dilute hydrochloric acid according to the equation: Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

## Mark scheme (4 marks)

1. The reaction is exothermic
2. Energy is transferred to the surroundings, causing the temperature to increase
3. On the reaction profile, the products are at a lower energy level than the reactants
4. The overall enthalpy change (ΔH) is negative / the difference in energy between reactants and products represents a negative enthalpy change

## Key terms

- [enthalpy change](https://www.gradenine.co.uk/glossary/enthalpy-change)
- [reaction profile](https://www.gradenine.co.uk/glossary/reaction-profile)

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- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/when-magnesium-ribbon-is-added-to-9574fb84) · Published by Druglandscape Ltd.