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, endothermic
102 kJ/mol, endothermic

–102 kJ/mol, exothermic

Answer 1

To calculate the total energy change of the reaction, we need to find the difference between the energy of the reactants and the energy of the products:

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

Substituting the values given:

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

Since the energy change is negative, this means the reaction releases energy to the surroundings. Therefore, the reaction is exothermic.

So the answer is:

–102 kJ/mol, exothermic