2. In a given reaction, the bond energy of the reactants is 920 kJ/mol, and the bond energy of the products is 1040 kJ/mol. What is the total energy of the reaction? Is the reaction endothermic or exothermic?

Question

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A. 1960 kJ/mol, endothermic
B. 120 kJ/mol, endothermic
C. -1960 kJ/mol, exothermic
D. -120 kJ/mol, exothermic

Answer 1

The total energy of the reaction can be calculated by subtracting the bond energy of the reactants from the bond energy of the products:

1040 kJ/mol - 920 kJ/mol = 120 kJ/mol

Since the total energy of the reaction is positive (120 kJ/mol), indicating that energy is absorbed during the reaction, the reaction is endothermic. Therefore, the correct answer is:

B. 120 kJ/mol, endothermic