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Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145당신이 사용하는 게 아니라요?교과서 변경
18장, 문제 43

The following reaction of A3 molecules is spontaneous. Illustration showing the spontaneous reaction of A3 molecules transitioning from a compact to a dispersed state.
(b) What are the signs of ∆H, ∆S, and ∆G for the reaction? Explain.

검증된 단계별 안내
1
Step 1: Identify the initial and final states of the A3 molecules from the image. Initially, the molecules are in a compact state, and finally, they are in a dispersed state.
Step 2: Determine the sign of ∆S (entropy change). Since the molecules are moving from a compact to a more dispersed state, the entropy (∆S) increases, so ∆S is positive.
Step 3: Determine the sign of ∆H (enthalpy change). For a spontaneous reaction, if the process involves breaking bonds or increasing molecular motion, it is likely that the enthalpy change (∆H) is positive, indicating an endothermic process.
Step 4: Determine the sign of ∆G (Gibbs free energy change). For a reaction to be spontaneous, the Gibbs free energy change (∆G) must be negative.
Step 5: Summarize the signs of ∆H, ∆S, and ∆G. Based on the analysis, ∆H is positive, ∆S is positive, and ∆G is negative for the spontaneous reaction.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
2m

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Enthalpy (∆H)

Enthalpy (∆H) is a measure of the total heat content of a system. In a spontaneous reaction, if the system releases heat to the surroundings, ∆H is negative, indicating an exothermic process. Conversely, if the system absorbs heat, ∆H is positive, indicating an endothermic process. Understanding the sign of ∆H helps determine whether the reaction is energetically favorable.
추천 영상:
가이드 코스
02:34
Enthalpy of Formation

Entropy (∆S)

Entropy (∆S) is a measure of the disorder or randomness in a system. A positive ∆S indicates an increase in disorder, which is often the case when molecules transition from a more ordered state to a more dispersed state, as seen in the provided image. In spontaneous reactions, an increase in entropy is typically favorable, contributing to the overall spontaneity of the process.
추천 영상:
가이드 코스
02:46
Entropy in Thermodynamics

Gibbs Free Energy (∆G)

Gibbs Free Energy (∆G) combines enthalpy and entropy to determine the spontaneity of a reaction at constant temperature and pressure. The relationship is given by the equation ∆G = ∆H - T∆S. For a reaction to be spontaneous, ∆G must be negative. Thus, understanding the signs of ∆H and ∆S is crucial for predicting the sign of ∆G and the spontaneity of the reaction.
추천 영상:
가이드 코스
01:51
Gibbs Free Energy of Reactions
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