Cl2 is a stable diatomic molecule. It can be decomposed to form two Cl atoms as shown below.
Cl2 → 2Cl(9)
Predict the change in enthalpy (AH) of this reaction.
A) AH is (-); endothermic
B) AH is (+); endothermic
C) AH is (-); exothermic
D) AH is (+); exothermic
E) AH = 0; thermoneutral

Option B: ΔH is (+); endothermic

Explanation:

From the reaction Cl2 → 2Cl(g) given, we can see that the number of moles on the left hand side is 1 while on right hand side, it is 2. This means the number of moles are increasing and it means that the randomness of the system has increased. Also, the bonds are being broken down.

Therefore, the reaction is endothermic. In endothermic reactions, ΔH is positive.

Thus, the correct option is option B.

false

because it does not have the potential to be entirely used up