Use the reaction equation and bond energies to answer the question.

Question

2H2O ---> 2H2 + O2

H-O: 467 kJ / mol

H-H: 432 kJ / mol

O=O: 498 kJ / mol

What is the total energy of the reaction? Is this an endothermic or exothermic reaction?

(1 point)
Responses

-506 kJ / mol, exothermic
-506 kJ / mol, exothermic

506 kJ / mol, exothermic
506 kJ / mol, exothermic

-506 kJ / mol, endothermic
-506 kJ / mol, endothermic

506 kJ / mol, endothermic

Answer 1

To find the total energy of the reaction, we need to calculate the energy change using bond energies.

In the reactant side, we have 2 H-O bonds and 1 O=O bond:
Energy in reactants = 2(467 kJ/mol) + 1(498 kJ/mol) = 1432 kJ/mol

In the product side, we have 4 H-H bonds:
Energy in products = 4(432 kJ/mol) = 1728 kJ/mol

Now, to find the total energy change:
Total energy change = Energy in products - Energy in reactants
= 1728 kJ/mol - 1432 kJ/mol
= 296 kJ/mol

Since the total energy change is positive, it means that energy is absorbed or taken in during the reaction. Therefore, this reaction is endothermic.

Therefore, the answer is:
506 kJ/mol, endothermic