Textbook Problem 5.33

[Antonia Valencia 2H]

Hi! For problem #5.33, I'm having a hard time understanding part a. My thought process was that because there are a lot more X2 reactants in container number one, this indicates that the initial reaction was primarily exothermic (because the reaction of forming a new bond between two X molecules into one X2 molecule would release energy). As such, I figured that increasing the temperature would therefore the products which, in the case of the reverse reaction, 2X --> X2, would be the X2 molecules. If this were the case, the second container does not contain many X2 molecules, and hence raising the temperature would not produce the depicted composition. However, this reasoning is wrong. Can someone help understand how to approach this problem? Thanks so much!

[Devika Nair 2D]

I think you might be interpreting the containers incorrectly. The first container is the equilibrium state of the reaction (reactants plus products) before a change, and the second container is the equilibrium state of the reaction (reactants plus products) after a change. Breaking a bond always requires energy input. Since the ONLY thing occurring in the forward reaction is the breaking of a diatomic molecule into its atomic components (X2-->2X), it must be an endothermic reaction. Another clue is that the reaction only occurs at 500K, a high temperature. Since it's endothermic, increasing the temperature would cause a shift towards the products (2X).