Use the bond energies below to determine whether the following reaction is exothermic or endothermic: H-H (bond energy: 436 kJ/mol) Cl-Cl (bond energy: 243 kJ/mol)
H-Cl (bond energy: 431 kJ/mol)

Question

Use the bond energies below to determine whether the following reaction is exothermic or endothermic:  H-H (bond energy: 436 kJ/mol) Cl-Cl (bond energy: 243 kJ/mol)
H-Cl (bond energy: 431 kJ/mol)

Quizplus · Accepted Answer

To determine the energy change of the reaction, we need to subtract the total energy required to break the bonds from the total energy released when new bonds are formed.

Breaking the H-H bond requires 436 kJ/mol and breaking the Cl-Cl bond requires 243 kJ/mol, for a total of 679 kJ/mol energy required.

Forming the H-Cl bond releases 431 kJ/mol of energy.

Therefore, the net energy change for the reaction is:

net energy = energy released - energy required
net energy = 431 kJ/mol - 679 kJ/mol
net energy = -248 kJ/mol

The negative sign indicates that the reaction is exothermic, meaning that energy is released during the reaction.

Since the magnitude of the net energy change is greater than 50 kJ/mol, we can conclude that the answer is A, Exothermic with more than 50 kJ of energy released.

Use the Bond Energies Below to Determine Whether the Following