CHE 1221 - Entropy/Spontaneity

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What is entropy (S)?

Back

Entropy (S) is a measure of the disorder or randomness in a system. It quantifies the number of possible arrangements of particles in a system.

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What does a positive change in entropy (ΔS > 0) indicate?

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A positive change in entropy (ΔS > 0) indicates that the disorder of the system has increased, often associated with spontaneous processes.

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What does a negative change in entropy (ΔS < 0) indicate?

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A negative change in entropy (ΔS < 0) indicates that the disorder of the system has decreased, often associated with non-spontaneous processes.

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How does temperature affect entropy?

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As temperature increases, the entropy of a system generally increases because higher temperatures provide more energy for particles to move and arrange themselves in more ways.

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What is the relationship between entropy and spontaneity?

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The Second Law of Thermodynamics states that for a process to be spontaneous, the total entropy of the system and surroundings must increase (ΔSuniverse > 0).

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What is standard molar entropy (S°)?

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Standard molar entropy (S°) is the entropy of one mole of a substance in its standard state at 1 bar and a specified temperature, usually 298 K.

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Which has higher standard molar entropy: gases, liquids, or solids?

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Gases have higher standard molar entropy than liquids, which in turn have higher entropy than solids due to greater molecular motion and disorder.

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What factors influence the standard molar entropy of a substance?

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Factors include molecular complexity, phase of matter, temperature, and the number of atoms in a molecule.

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How do molecular size and structure affect entropy?

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Larger and more complex molecules generally have higher entropy due to more possible arrangements and greater molecular motion.

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What is the significance of the Third Law of Thermodynamics?

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The Third Law of Thermodynamics states that as the temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.