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)
-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 calculate the total energy of the reaction, we need to consider the bond energies of the reactants and the products.

Reactants:
2H-O (H2O) bonds = 2 * 467 kJ/mol = 934 kJ/mol

Products:
2H-H (H2) bonds = 2 * 432 kJ/mol = 864 kJ/mol
1O=O (O2) bond = 1 * 498 kJ/mol = 498 kJ/mol

Total energy change = total energy of bonds broken - total energy of bonds formed

Total energy change = (2 * H-O bond energy) - (2 * H-H bond energy) - (1 * O=O bond energy)
Total energy change = (2 * 467 kJ/mol) - (2 * 432 kJ/mol) - (1 * 498 kJ/mol)
Total energy change = 934 kJ/mol - 864 kJ/mol - 498 kJ/mol
Total energy change = -428 kJ/mol

Since the total energy change is negative (-428 kJ/mol), this reaction is exothermic.

Answer 2

whats the answer

Answer 3

The answer is:

-506 kJ/mol, exothermic