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, endothermic
–102 kJ/mol, endothermic

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

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

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

Answer 1

To determine the total energy change of the reaction, we can calculate the difference between the energy of the reactants and the energy of the products.

The energy of the reactants (HBr) is given as 732 kJ/mol, and the energy of the products (H2 and Br2) is 630 kJ/mol.

The formula for the energy change (ΔE) in a reaction is:

\[ \Delta E = E_{\text{products}} - E_{\text{reactants}} \]

Substituting the values:

\[ \Delta E = 630 \text{ kJ/mol} - 732 \text{ kJ/mol} = -102 \text{ kJ/mol} \]

Since the value is negative, it indicates that the energy is released in the reaction. Therefore, this reaction is exothermic.

The correct response is:

–102 kJ/mol, exothermic