Consider the reaction: C3H8(g) + 5 O2(g) ® 3 CO2(g) + 4 H2O(g), where DH = – 531 kcal/mol. Which statement is true?

A.Heat is absorbed.
B.The bonds formed in the products are stronger than the bonds broken in the reactants.
C.The products are higher in energy than the reactants.
D.The reaction is endothermic.

The correct answer is D. The reaction is endothermic.

Explanation:
An endothermic reaction is a reaction that absorbs heat from its surroundings. In this reaction, the enthalpy change (DH) is negative, which means that energy is absorbed. Consequently, the products have higher energy than the reactants.

To determine which statement is true for the given reaction, we need to analyze the enthalpy change (ΔH) associated with it.

The ΔH value for the reaction is -531 kcal/mol. This value indicates whether the reaction is exothermic (heat is released) or endothermic (heat is absorbed).

Based on the ΔH value being negative (-531 kcal/mol), we can conclude that the reaction is exothermic. This means that heat is released during the reaction.

Therefore, the correct statement is:

A. Heat is absorbed.

Option B (The bonds formed in the products are stronger than the bonds broken in the reactants) cannot be determined solely based on the ΔH value, as it relates to the bond strengths. Option C (The products are higher in energy than the reactants) is not accurate because an exothermic reaction generally results in lower energy products compared to the reactants. Option D (The reaction is endothermic) is incorrect because the given ΔH value indicates an exothermic process.

Heat is given off and the reaction is exothermic.

-4088 kJ