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

Answer 1

To determine the total energy of the reaction and whether it is endothermic or exothermic, we need to calculate the difference in energy between the reactants and 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 change in energy (ΔE) for the reaction can be calculated as follows:

\[ ΔE = \text{Energy of products} - \text{Energy of reactants} \] \[ ΔE = 630 , \text{kJ/mol} - 732 , \text{kJ/mol} \] \[ ΔE = -102 , \text{kJ/mol} \]

Since the value is negative, it indicates that energy is released during the reaction, which means the reaction is exothermic.

Therefore, the correct response is:

–102 kJ/mol, exothermic