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, exothermic
–102 kJ/mol, exothermic

102 kJ/mol, endothermic

Answer 1

To determine the total energy change of the reaction, we can use the following formula:

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

Given that the energy of the reactants (HBr) is 732 kJ/mol and the energy of the products (H2 and Br2) is 630 kJ/mol, we can calculate the energy change:

\[ \text{Energy change} = 630 \text{ kJ/mol} - 732 \text{ kJ/mol} = -102 \text{ kJ/mol} \]

Since the energy change is negative, this indicates that the reaction releases energy, making it exothermic.

Therefore, the answer is:

–102 kJ/mol, exothermic