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Ch.19 - Chemical Thermodynamics
Brown - Chemistry: The Central Science 15th Edition
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Tutti i libri di testoBrown 15th EditionCh.19 - Chemical ThermodynamicsProblema 79
Capitolo 19, Problema 79

Use data from Appendix C to calculate the equilibrium constant, K, and ΔG° at 298 K for each of the following reactions: (a) H2(g) + I2(g) ⇌ 2 HI(g) (b) C2H5OH(g) ⇌ C2H4(g) + H2O(g) (c) 3 C2H2(g) ⇌ C6H6(g)

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Step 1: Identify the standard Gibbs free energy of formation (ΔG°f) for each reactant and product from Appendix C for each reaction at 298 K.
Step 2: Calculate the standard Gibbs free energy change (ΔG°) for each reaction using the formula: ΔG° = Σ(ΔG°f of products) - Σ(ΔG°f of reactants).
Step 3: Use the relationship between ΔG° and the equilibrium constant (K) given by the equation: ΔG° = -RT ln(K), where R is the universal gas constant (8.314 J/mol·K) and T is the temperature in Kelvin (298 K).
Step 4: Rearrange the equation from Step 3 to solve for the equilibrium constant (K): K = e^(-ΔG°/RT).
Step 5: Substitute the calculated ΔG° from Step 2 into the equation from Step 4 to find the equilibrium constant (K) for each reaction.

Concetti chiave

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

Equilibrium Constant (K)

The equilibrium constant, K, is a dimensionless value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. It is calculated using the formula K = [products]^[coefficients] / [reactants]^[coefficients]. A large K value indicates that products are favored at equilibrium, while a small K value suggests that reactants are favored.
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Equilibrium Constant K

Gibbs Free Energy (ΔG°)

Gibbs free energy, ΔG°, is a thermodynamic potential that indicates the spontaneity of a reaction at constant temperature and pressure. It is related to the equilibrium constant by the equation ΔG° = -RT ln(K), where R is the universal gas constant and T is the temperature in Kelvin. A negative ΔG° value suggests that the reaction is spontaneous in the forward direction.
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Gibbs Free Energy of Reactions

Standard Conditions

Standard conditions refer to a set of specific conditions (usually 1 atm pressure and 298 K temperature) under which thermodynamic measurements are made. These conditions are essential for calculating standard Gibbs free energy changes and equilibrium constants, ensuring consistency and comparability of data across different reactions and studies.
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Standard Reduction Potentials
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