Reaction A: Reaction B: Average bond energies ( ): H–H 436, Cl–Cl 243, O=O 498, H–Cl…

CHEMISTRY · Subjective · A Level · Chemistry · Energetics · Energetics

Problem

Reaction A: H2(g)+Cl2(g)→2 HCl(g)\mathrm{H_2(g) + Cl_2(g) \rightarrow 2\,HCl(g)} Reaction B: H2(g)+12 O2(g)→H2O(g)\mathrm{H_2(g) + \tfrac12\,O_2(g) \rightarrow H_2O(g)} Average bond energies (kJ mol−1\text{kJ mol}^{-1}): H–H 436, Cl–Cl 243, O=O 498, H–Cl 431, O–H 463. Identify which reaction is more exothermic and briefly justify your choice based on the data provided.

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