The reaction proceeds spontaneously at 298 cap k NH sub 3 times g plus Cl sub 2 times g rightarrow NH sub 4 Cl s What is the sign of the entropy change, triangle cap s ?

The reactants are gases, which have many possible arrangements and are relatively disordered. The product is a solid, whose particles are more ordered and have fewer possible arrangements. Since entropy decreases as the reaction forms the less-random solid, ΔS is negative; this matches choice C.

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