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, endothermic
102 kJ/mol, endothermic

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

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

Answer 1

To determine the total energy of the reaction and whether it is endothermic or exothermic, we can calculate the change in energy (\( \Delta E \)) using the formula:

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

Given:

• Energy of the reactants (HBr): 732 kJ/mol
• Energy of the products (H₂ and Br₂): 630 kJ/mol

Now we can plug in the values:

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

The negative sign indicates that energy is released during the reaction.

Since \( \Delta E \) is negative, the reaction is exothermic.

Therefore, the correct response is:

–102 kJ/mol, exothermic