Exothermic reaction?

Exothermic reaction?

• A. A chemical reaction that releases energy to its surroundings.
• B. A chemical reaction that absorbs energy.
• C. A reaction that requires catalysts.
• D. A reaction that does not involve energy transfer.

Answer: (A)

Exothermic reactions release energy to their surroundings, usually as heat, which is why the surroundings get warmer. This means the reaction has a negative enthalpy change (ΔH < 0). That’s exactly what the statement describes: a chemical reaction that releases energy to its surroundings. The other ideas don’t define exothermic behavior. A reaction that absorbs energy describes an endothermic process, not exothermic. A reaction that requires catalysts speaks to reaction rate (how fast it happens), not the energy change involved. And a reaction that does not involve energy transfer isn’t accurate, since all chemical reactions involve some transfer of energy as bonds break and form.

Exothermic reactions release energy to their surroundings, usually as heat, which is why the surroundings get warmer. This means the reaction has a negative enthalpy change (ΔH < 0).

That’s exactly what the statement describes: a chemical reaction that releases energy to its surroundings. The other ideas don’t define exothermic behavior. A reaction that absorbs energy describes an endothermic process, not exothermic. A reaction that requires catalysts speaks to reaction rate (how fast it happens), not the energy change involved. And a reaction that does not involve energy transfer isn’t accurate, since all chemical reactions involve some transfer of energy as bonds break and form.