Question

Using the bond dissociation energies given, calculate ΔH° for the following reaction.

A) Exothermic
B) Endothermic
C) Isobaric
D) Isothermal

Answer 1

The enthalpy change (ΔH°) for a chemical reaction can be calculated by subtracting the total bond energy of bonds formed in products from the total bond energy of bonds broken in reactants. If ΔH° is negative, the reaction is exothermic; if positive, it's endothermic.

Step-by-step explanation:

To determine if a chemical reaction is exothermic or endothermic using bond dissociation energies, we need to follow these steps:

1. Calculate the total bond dissociation energy for all bonds broken in the reactants. This is endothermic (requires energy).
2. Calculate the total bond dissociation energy for all bonds formed in the products. This is exothermic (releases energy).
3. Subtract the energy of bonds formed from the energy of bonds broken to obtain the overall enthalpy change (ΔH°) for the reaction.

If ΔH° is negative, the reaction is exothermic, meaning it releases heat. If ΔH° is positive, the reaction is endothermic, meaning it absorbs heat.

Options A) Exothermic and B) Endothermic refer to whether heat is given off or absorbed. Options C) Isobaric and D) Isothermal refer to constant pressure and temperature, respectively, and are not directly related to the calculation of ΔH° using bond dissociation energies.