Question detail
If the entropy change (ΔS) for a reaction is positive, what can be inferred about the disorder of the system?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Thermodynamics (A-level only)
Question
- A. The disorder of the system decreases.
- B. The disorder of the system increases.
- C. The system remains unchanged.
- D. The reaction is non-spontaneous.
Answer
The disorder of the system increases.
Explanation
A positive entropy change (ΔS) indicates that the disorder or randomness of the system increases, which can contribute to the spontaneity of a reaction when combined with enthalpy changes.
Common mistake
Misunderstanding Gibbs Free Energy
Students often confuse the signs of ΔH and ΔS when predicting reaction feasibility using ΔG = ΔH - TΔS.
To fix this, remember that ΔG must be negative for a reaction to be feasible. Clearly identify the signs of ΔH and ΔS before substituting into the formula. For example, if ΔH is positive and ΔS is positive, the temperature will influence the sign of ΔG. Substitute values correctly: ΔG = ΔH - TΔS, then calculate and conclude whether the reaction is feasible based on the sign of ΔG.
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