Answer:
N₂O₄ + 14 kcal ⇄ 2NO₂.
Explanation:
Since the sign of ΔH determines either the reaction is exothermic or endothermic:
+ve, the reaction is endothermic.
-ve, the reaction is exothermic.
∵ The change of enthalpy of this reaction when proceeding left to right is + 14 kcal (+ ve sign).
∴ The reaction is endothermic, the heat is a part of the reacatnts in the reaction.
So, the reaction is:
N₂O₄ + 14 kcal ⇄ 2NO₂.