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Ch.18 - Free Energy and Thermodynamics
Tro - Chemistry: A Molecular Approach 4th Edition
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Tro 4th EditionCh.18 - Free Energy and Thermodynamics문제 70c
18장, 문제 70c

Consider the evaporation of methanol at 25.0 °C : CH3OH(l) → CH3OH(g) c. Explain why methanol spontaneously evaporates in open air at 25.0 °C

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1
insert step 1: Understand the concept of spontaneity in thermodynamics. A process is spontaneous if it occurs without needing to be driven by an external force.
insert step 2: Consider the Gibbs free energy change (ΔG) for the evaporation process. A process is spontaneous if ΔG is negative.
insert step 3: Use the equation ΔG = ΔH - TΔS, where ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy.
insert step 4: Recognize that evaporation involves a phase change from liquid to gas, which increases the disorder or entropy (ΔS > 0) of the system.
insert step 5: Even if the enthalpy change (ΔH) is positive (endothermic), the increase in entropy (ΔS) can make the TΔS term large enough to result in a negative ΔG, making the process spontaneous.

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주요 개념

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

Evaporation

Evaporation is the process by which molecules at the surface of a liquid gain enough energy to enter the gas phase. This occurs when some molecules have sufficient kinetic energy to overcome intermolecular forces, allowing them to escape into the air. The rate of evaporation increases with temperature, as higher temperatures provide more molecules with the energy needed to evaporate.
추천 영상:
가이드 코스
04:50
Filtration and Evaporation

Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid at a given temperature. For methanol at 25.0 °C, the vapor pressure is significant enough that some molecules will escape into the air, leading to spontaneous evaporation. When the vapor pressure exceeds the atmospheric pressure, evaporation occurs more readily.
추천 영상:
가이드 코스
02:40
Raoult's Law and Vapor Pressure

Thermodynamics and Spontaneity

Thermodynamics helps explain the spontaneity of processes based on changes in energy and entropy. The evaporation of methanol is spontaneous at 25.0 °C because it increases the entropy of the system; as liquid methanol transitions to gas, the disorder increases, favoring the process. This aligns with the second law of thermodynamics, which states that spontaneous processes tend to increase the overall entropy of the universe.
추천 영상:
가이드 코스
04:20
Spontaneity of Processes
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