What is the enthalpy sign for endothermic reactions?

What is the enthalpy sign for endothermic reactions?

• A. Negative
• B. Zero
• C. Undefined
• D. Positive

Answer: (D)

In the context of thermochemistry, an endothermic reaction is characterized by the absorption of heat from the surroundings. During such a reaction, the system takes in thermal energy, which leads to a decrease in the temperature of the surroundings. This heat absorbed is associated with a positive change in enthalpy (ΔH) for the reaction. When calculating enthalpy changes, if a reaction absorbs heat, it indicates that the energy of the products is higher than that of the reactants. This positive value reflects the energy input required to drive the reaction forward. Therefore, for endothermic reactions, the correct sign for the enthalpy change is indeed positive. This is crucial for understanding energy changes in chemical processes and how they affect reaction spontaneity and equilibrium.

In the context of thermochemistry, an endothermic reaction is characterized by the absorption of heat from the surroundings. During such a reaction, the system takes in thermal energy, which leads to a decrease in the temperature of the surroundings. This heat absorbed is associated with a positive change in enthalpy (ΔH) for the reaction.

When calculating enthalpy changes, if a reaction absorbs heat, it indicates that the energy of the products is higher than that of the reactants. This positive value reflects the energy input required to drive the reaction forward. Therefore, for endothermic reactions, the correct sign for the enthalpy change is indeed positive. This is crucial for understanding energy changes in chemical processes and how they affect reaction spontaneity and equilibrium.