A negative ΔH value indicates what about the forward reaction?

A negative ΔH value indicates what about the forward reaction?

• A. Heat is released
• B. Heat is absorbed
• C. No heat change
• D. Temperature always rises

Answer: (A)

Negative ΔH means the reaction releases heat to the surroundings. ΔH is the heat exchanged at constant pressure, so a negative value indicates the system loses energy as heat, making the forward reaction exothermic. That’s why heat is released. If heat were absorbed, ΔH would be positive and the process would be endothermic. If there were no heat change, ΔH would be zero. The idea that the temperature always rises isn’t guaranteed, since temperature change depends on how the heat is transferred and the surroundings’ ability to absorb it.

Negative ΔH means the reaction releases heat to the surroundings. ΔH is the heat exchanged at constant pressure, so a negative value indicates the system loses energy as heat, making the forward reaction exothermic. That’s why heat is released.

If heat were absorbed, ΔH would be positive and the process would be endothermic. If there were no heat change, ΔH would be zero. The idea that the temperature always rises isn’t guaranteed, since temperature change depends on how the heat is transferred and the surroundings’ ability to absorb it.