AQA A-level Chemistry Calculating Reaction ΔE
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Bond enthalpies are measured for one mole of bonds in the gaseous state and are always endothermic. They can be used to measure energy change for a reaction by following these 3 steps.
Energy change of reaction may need to be calculated to determine whether a reaction is exothermic or endothermic and sketch the reaction profile.
Work out the energy change of this reaction: H₂(g) + Cl₂(g) → 2HCl(g) given the bond enthalpies; H—H +436 kJ/mol, Cl—Cl +242 kJ/mol, H--Cl +431 kJ/mol. Is this an endothermic or an exothermic reaction?
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