Question

question 7 for the combustion of ethylene, why does entropy decrease? because the products are more ordered than the reactants. because the reactants are more ordered than the products. because the reaction absorbs heat. because the reaction releases heat.

Explanation:

1. Recall the definition of entropy: Entropy (\(S\)) is a measure of disorder or randomness in a system. A decrease in entropy means the system becomes more ordered (less random).
2. Analyze the options:

• Option 1: "Because the products are more ordered than the reactants." If products are more ordered, the disorder (entropy) decreases. This matches the concept of entropy decrease.
• Option 2: If reactants were more ordered than products, entropy would increase (since products are less ordered), so this is incorrect.
• Option 3: Combustion reactions (like ethylene combustion: \(C_2H_4 + 3O_2

ightarrow 2CO_2 + 2H_2O\)) are exothermic (release heat), not endothermic (absorb heat). So this is incorrect.

• Option 4: While combustion releases heat, the reason for entropy decrease is about order, not heat release (heat release relates to enthalpy, not directly entropy change's order - based cause here). So this is incorrect.

Answer:

A. Because the products are more ordered than the reactants.