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Ch.18 - Free Energy and Thermodynamics
Tro - Chemistry: A Molecular Approach 4th Edition
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Tutti i libri di testoTro 4th EditionCh.18 - Free Energy and ThermodynamicsProblema 43
Capitolo 18, Problema 43

Calculate the change in Gibbs free energy for each set of ΔHrxn, ΔSrxn, and T given in Problem 41. Predict whether or not each reaction is spontaneous at the temperature indicated. (Assume that all reactants and products are in their standard states.)

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Identify the given values for each reaction: \( \Delta H_{rxn} \) (enthalpy change), \( \Delta S_{rxn} \) (entropy change), and \( T \) (temperature in Kelvin).
Use the Gibbs free energy equation: \( \Delta G = \Delta H - T \Delta S \) to calculate the change in Gibbs free energy for each reaction.
Substitute the given values into the equation for each reaction to find \( \Delta G \).
Determine the spontaneity of each reaction: if \( \Delta G < 0 \), the reaction is spontaneous; if \( \Delta G > 0 \), the reaction is non-spontaneous.
Summarize the results for each reaction, indicating whether it is spontaneous or not at the given temperature.

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Gibbs Free Energy (G)

Gibbs free energy is a thermodynamic potential that measures the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure. It is defined by the equation G = H - TS, where H is enthalpy, T is temperature, and S is entropy. A negative change in Gibbs free energy (ΔG < 0) indicates that a reaction is spontaneous, while a positive change (ΔG > 0) suggests non-spontaneity.
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Gibbs Free Energy of Reactions

Enthalpy (ΔH)

Enthalpy is a measure of the total heat content of a system and is used to quantify the energy changes during chemical reactions. The change in enthalpy (ΔH) can be either positive or negative, indicating whether a reaction absorbs heat (endothermic, ΔH > 0) or releases heat (exothermic, ΔH < 0). This value is crucial for determining the spontaneity of a reaction when combined with entropy changes.
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Enthalpy of Formation

Entropy (ΔS)

Entropy is a measure of the disorder or randomness in a system. The change in entropy (ΔS) during a reaction reflects how the distribution of energy changes, with positive ΔS indicating increased disorder and negative ΔS indicating decreased disorder. In the context of Gibbs free energy, a positive ΔS can favor spontaneity, especially at higher temperatures, as it contributes to a more negative ΔG.
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Entropy in Thermodynamics
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