To calculate the total change in bond energy for the reaction H2 + Cl2 -> 2HCl, you would subtract the sum of the bond energies of the reactants (432 + 239 = 671) from the sum of the bond energies of the products (2 x 427 = 854). The difference between the two sums (854 - 671 = 183) is the total change in bond energy for the reaction.
To determine if the reaction is endothermic or exothermic, you would compare the total change in bond energy to zero. If the total change in bond energy is positive, then the reaction is endothermic. If the total change in bond energy is negative, then the reaction is exothermic. In this case, the total change in bond energy is positive, so the reaction is endothermic.
Bond Bond Energy
H-H 432
Cl-Cl 239
H-Cl 427
Explain how you would calculate the total change in bond energy for the reaction H2 + Cl2 -> 2HCl. How would you know if the reaction was endothermic or exothermic?
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