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3. (a) When ammonium nitrate dissolves in water, the change is endothermic - Edexcel - GCSE Chemistry - Question 3 - 2016 - Paper 1
Question 3
3. (a) When ammonium nitrate dissolves in water, the change is endothermic. In an experiment, a thermometer is placed in some water in a beaker and ammonium nitrate... show full transcript
Worked Solution & Example Answer:3. (a) When ammonium nitrate dissolves in water, the change is endothermic - Edexcel - GCSE Chemistry - Question 3 - 2016 - Paper 1
Step 1
State what you would see to show that the reaction is endothermic.
Answer
In an endothermic reaction, you would observe that the thermometer reading decreases as ammonium nitrate dissolves in water. This indicates that the system absorbs heat from the surroundings, resulting in a drop in temperature.
Step 2
Explain, in terms of the breaking of bonds and the making of bonds, why this reaction is exothermic.
Answer
The reaction between hydrogen and chlorine is exothermic because when bonds are formed, energy is released. Specifically, the energy required to break the bonds in the reactants (H₂ and Cl₂) is less than the energy released when new bonds are formed in the product (2 HCl). This net release of energy during the formation of the HCl bonds results in an overall exothermic reaction.