Using the following bond dissociation data, determine the enthalpy change for the conversion $8S(s) + \tfrac32 S_8(g)$.

+512.0 kcal
-512.0 kcal
508.0 kcal
-508.0 kcal

Correct answer: -508.0 kcal

Solution

The reaction is a bond-energy bookkeeping problem. Converting sulfur in its molecular form to atoms requires energy, and the reverse formation of $S_8$ releases the same amount; combining the given data through Hess’s law gives a net enthalpy change of $-508.0$ kcal.

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