Which term describes reactions that release energy as heat?

Which term describes reactions that release energy as heat?

• A. Exothermic
• B. Endothermic
• C. Isothermal
• D. Adiabatic

Answer: (A)

Releasing energy as heat means the system loses energy to its surroundings, warming them. That behavior is described as exothermic. In an exothermic reaction, heat is emitted, so the surroundings rise in temperature (think of combustion or a hand warmer). The opposite term, endothermic, describes reactions that absorb heat from the surroundings, often making the surroundings feel cooler. Isothermal refers to processes that stay at a constant temperature, typically requiring heat flow to maintain that temperature. Adiabatic means no heat is exchanged with the surroundings, so temperature can change without heat transfer.

Releasing energy as heat means the system loses energy to its surroundings, warming them. That behavior is described as exothermic. In an exothermic reaction, heat is emitted, so the surroundings rise in temperature (think of combustion or a hand warmer). The opposite term, endothermic, describes reactions that absorb heat from the surroundings, often making the surroundings feel cooler. Isothermal refers to processes that stay at a constant temperature, typically requiring heat flow to maintain that temperature. Adiabatic means no heat is exchanged with the surroundings, so temperature can change without heat transfer.