If ΔS is positive, which statement is true?

If ΔS is positive, which statement is true?

• A. Products are more disordered than reactants
• B. Reactants are more disordered than products
• C. Entropy decreases
• D. Reaction is always favorable

Answer: (A)

When entropy increases, the system becomes more disordered, meaning there are more ways to arrange the energy among the particles. In a reaction, a positive ΔS means the products have a greater number of accessible microstates than the reactants, so the products are more disordered than the reactants. This is exactly what a positive ΔS indicates. Entropy rising does not automatically make a reaction favorable overall. The spontaneity of a reaction depends on ΔG = ΔH − TΔS. If the enthalpy change ΔH is very large and positive, the term ΔH − TΔS could still be positive, making the reaction nonspontaneous even with a positive ΔS. So the statement that best matches a positive ΔS is that the products are more disordered than the reactants.

When entropy increases, the system becomes more disordered, meaning there are more ways to arrange the energy among the particles. In a reaction, a positive ΔS means the products have a greater number of accessible microstates than the reactants, so the products are more disordered than the reactants. This is exactly what a positive ΔS indicates.

Entropy rising does not automatically make a reaction favorable overall. The spontaneity of a reaction depends on ΔG = ΔH − TΔS. If the enthalpy change ΔH is very large and positive, the term ΔH − TΔS could still be positive, making the reaction nonspontaneous even with a positive ΔS.

So the statement that best matches a positive ΔS is that the products are more disordered than the reactants.