Using the bond energies (kJ/mol) H–H 436, Cl–Cl 243, H–Cl 432, estimate the enthalpy change for H + Cl → 2HCl.

Answer and explanation

Correct answer: A. -185 kJ

  1. Step 1: .
  2. Step 2: Substituting the bond energies gives kJ.
Answer
-185 kJ.
Why not the others: +185 kJ: the sign is reversed, which would make the reaction endothermic.

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Using the bond energies (kJ/mol)… | EJU Japan Thermochemistry