Question

question 14 of 25
what is known about a reaction with a positive enthalpy?
a. heat is given off as a product of the reaction.
b. the reaction has a large activation energy.
c. heat is required to make the reaction occur.
d. the reaction will never be spontaneous.

Explanation:

Enthalpy change ($\Delta H$) is positive for endothermic reactions. In endothermic reactions, heat is absorbed from the surroundings for the reaction to occur. Option A describes an exothermic reaction ($\Delta H<0$). Activation energy is not directly related to the sign of enthalpy. A reaction with positive $\Delta H$ can be spontaneous under certain conditions (when $\Delta G < 0$, considering entropy change as well, $\Delta G=\Delta H - T\Delta S$).

Answer:

C. Heat is required to make the reaction occur.