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Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium
McMurry - Chemistry 8th Edition
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Tutti i libri di testoMcMurry 8th EditionCh.18 - Thermodynamics: Entropy, Free Energy & EquilibriumProblema 8
Capitolo 18, Problema 8

Calculate ∆Stotal, and determine whether the reaction is spon-taneous or nonspontaneous under standard-state conditions. (a) -429 J/K; nonspontaneous (b) -123 J/K; spontaneous (c) +3,530 J/K; nonspontaneous (d) +184 J/K; nonspontaneous

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Identify the given values for \( \Delta S_{\text{total}} \) in each option.
Recall that a reaction is spontaneous if \( \Delta S_{\text{total}} > 0 \) and nonspontaneous if \( \Delta S_{\text{total}} < 0 \).
Analyze each option: (a) \( \Delta S_{\text{total}} = -429 \text{ J/K} \), (b) \( \Delta S_{\text{total}} = -123 \text{ J/K} \), (c) \( \Delta S_{\text{total}} = +3,530 \text{ J/K} \), (d) \( \Delta S_{\text{total}} = +184 \text{ J/K} \).
Determine the spontaneity of each option based on the sign of \( \Delta S_{\text{total}} \).
Match the spontaneity conclusion with the given options to identify the correct answer.

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Gibbs Free Energy

Gibbs Free Energy (G) is a thermodynamic potential that helps predict the spontaneity of a reaction at constant temperature and pressure. A reaction is spontaneous if the change in Gibbs Free Energy (∆G) is negative. The relationship between Gibbs Free Energy, enthalpy (H), and entropy (S) is given by the equation ∆G = ∆H - T∆S, where T is the temperature in Kelvin.
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Gibbs Free Energy of Reactions

Entropy (S)

Entropy is a measure of the disorder or randomness in a system. In thermodynamics, an increase in entropy (∆S > 0) generally favors spontaneity, as systems tend to evolve towards states of higher disorder. The total entropy change (∆Stotal) for a reaction includes both the system and the surroundings, and a positive ∆Stotal indicates a spontaneous process.
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Entropy in Thermodynamics

Standard-State Conditions

Standard-state conditions refer to a set of specific conditions used to measure and compare thermodynamic properties, typically defined as 1 bar of pressure and a specified temperature (usually 25°C). Under these conditions, the standard enthalpy and entropy values are used to calculate the Gibbs Free Energy change, allowing for the assessment of reaction spontaneity in a consistent manner.
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Standard Reduction Potentials
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