2) If, when electrolyzing water (2H2O --> 2H2 + O2), the total bond energy of the reactants is 2000kJ and the total bond energy of the products is 934kJ, what is the total energy of the reaction and is this an endothermic or exothermic reaction?
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2 points
1066kJ, exothermic
-1066kJ, exothermic
-1066kJ, endothermic
1066kJ, endothermic
To find the total energy of the reaction, we subtract the total bond energy of the reactants from the total bond energy of the products:
Total energy of the reaction = Total bond energy of the products - Total bond energy of the reactants
Total energy of the reaction = 934 kJ - 2000 kJ = -1066 kJ
The total energy of the reaction is -1066 kJ. Since the reaction releases energy (the total energy is negative), the reaction is exothermic.
Therefore, the correct answer is:
-1066 kJ, exothermic