Answer:
The total change in energy is -183 kJ/mol, and the reaction is exothermic.
Explanation:
1st) To calculate the total change in bond energy, it is necessary to calculate the energy of the broken bonds (in the reactants side) and the energy of the formed bonds (in the products side):
• Energy of broken bonds:
H-H: 1 x 432 = 432 kJ/mol
Cl-Cl: 1 x 239 = 239 kJ/mol
Total energy of broken bonds = 432 kJ/mol + 239 kJ/mol
Total energy of broken bonds = 671 kJ/mol
• Energy of formed bonds:
H-Cl: 2 x 427 = 854 kJ/mol
Total energy of formed bonds = 854 kJ/mol
2nd) Now to calculate the total change in bond energy, we have to subtract the Total energy of broken bonds minus the total energy of the formed bonds:
Total change in energy = Total energy of broken bonds - Total energy of formed bonds
Total change in energy = 671 kJ/mol - 854 kJ/mol
Total change in energy = -183 kJ/mol
Finally, the total change in energy is -183 kJ/mol, and the negative sign means that the reaction is exothermic, because
