Hydrogen bromide breaks down into diatomic hydrogen and bromine in the reaction shown.

Question

2HBr → H2 + Br2

The energy of the reactant is 732 kJ/mol, and the energy of the products is 630 kJ/mol.

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

(1 point)
Responses

–102 kJ/mol, exothermic
–102 kJ/mol, exothermic

102 kJ/mol, endothermic
102 kJ/mol, endothermic

–102 kJ/mol, endothermic
–102 kJ/mol, endothermic

102 kJ/mol, exothermic

Answer 1

To calculate the total energy of the reaction, you subtract the energy of the products from the energy of the reactants:

\[ \text{Energy of the reaction} = \text{Energy of the reactants} - \text{Energy of the products} \]

Substituting in the values given:

\[ \text{Energy of the reaction} = 732 , \text{kJ/mol} - 630 , \text{kJ/mol} = 102 , \text{kJ/mol} \]

Since the result is positive, it indicates that the reaction requires energy, which means it is endothermic.

Thus, the correct response is:

102 kJ/mol, endothermic.