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Exothermic and endothermic reactions answer explanations

Review worked answers and explanations for Exothermic and endothermic reactions. Aligned to AQA Gcse Chemistry.

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Question 1

A self‑heating can contains 0.50 g of a mixture that reacts with oxygen to produce CO₂ and H₂O. The reaction can be approximated by the balanced equation: C₂H₅OH(l) + 3 O₂(g) → 2 CO₂(g) + 3 H₂O(l). Using the following average bond energies (kJ mol⁻¹): C–C 347, C–H 413, O–H 463, C=O 799, O=O 498, C–O 358, O–H (in water) 463, C–O (in CO₂) 799, O–O (in O₂) 498, calculate the total energy released (in kJ) when 0.50 g of ethanol reacts completely. (Assume the can contains pure ethanol.)