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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
What you would see to show that the reaction is endothermic
Answer
When ammonium nitrate dissolves in water, the thermometer reading will fall, indicating that the solution is absorbing heat from the surroundings. This temperature decrease is evidence of the endothermic nature of the reaction.
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 to form hydrogen chloride involves the breaking of H–H bonds and Cl–Cl bonds in the reactants.
Breaking bonds requires energy, which is absorbed during this process. However, when new H–Cl bonds are formed in the product, this process releases more energy than what was initially absorbed.
Ultimately, since more energy is released during bond formation than is consumed in bond breaking, the overall reaction is exothermic.