Skip to main content
Ch.19 - Free Energy & Thermodynamics
Tro - Chemistry: A Molecular Approach 6th Edition
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoTro 6th EditionCh.19 - Free Energy & ThermodynamicsProblema 84
Capitolo 19, Problema 84

Consider the reaction: 2 NO(g) + O2(g) ⇌ 2 NO2(g) The following data show the equilibrium constant for this reaction measured at several different temperatures. Use the data to find ΔH°rxn and ΔS°rxn for the reaction.

Guida verificata passo dopo passo
1
Identify the relationship between the equilibrium constant \( K \) and temperature \( T \) using the van 't Hoff equation: \( \ln K = -\frac{\Delta H^\circ}{R} \left( \frac{1}{T} \right) + \frac{\Delta S^\circ}{R} \).
Plot \( \ln K \) versus \( \frac{1}{T} \) using the given data. This will yield a straight line where the slope is \( -\frac{\Delta H^\circ}{R} \) and the y-intercept is \( \frac{\Delta S^\circ}{R} \).
Determine the slope of the line from the plot. Use the slope to calculate \( \Delta H^\circ \) by rearranging the equation: \( \Delta H^\circ = -\text{slope} \times R \), where \( R \) is the ideal gas constant (8.314 J/mol·K).
Determine the y-intercept of the line from the plot. Use the y-intercept to calculate \( \Delta S^\circ \) by rearranging the equation: \( \Delta S^\circ = \text{y-intercept} \times R \).
Summarize the calculated values of \( \Delta H^\circ \) and \( \Delta S^\circ \) for the reaction.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
8m

Concetti chiave

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

Equilibrium Constant (K)

The equilibrium constant (K) quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. It provides insight into the extent of the reaction and is temperature-dependent. For the reaction 2 NO(g) + O2(g) ⇌ 2 NO2(g), K can be used to determine how favorably the products are formed compared to the reactants.
Video consigliato:
Percorso guidato
01:14
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 gas constant and T is the temperature in Kelvin. A negative ΔG° suggests that the reaction is spontaneous in the forward direction.
Video consigliato:
Percorso guidato
01:51
Gibbs Free Energy of Reactions

Thermodynamic Parameters (ΔH° and ΔS°)

The standard enthalpy change (ΔH°) and standard entropy change (ΔS°) are key thermodynamic parameters that describe the heat and disorder changes during a reaction. They can be derived from the temperature dependence of the equilibrium constant using the van 't Hoff equation, which relates changes in K with temperature to ΔH° and ΔS°: d(ln K)/dT = ΔH°/(RT²).
Video consigliato:
Percorso guidato
01:18
First Law of Thermodynamics
Pratica correlata
Domanda del libro di testo

Determine the sign of ΔSsys for each process. a. water boiling

1191
views
Domanda del libro di testo

Determine the sign of ΔSsys for each process. b. water freezing

625
views
Domanda del libro di testo

A reaction has an equilibrium constant of 8.5⨉103 at 298 K. At 755 K, the equilibrium constant is 55.2. Find ΔH°rxn for the reaction.

Domanda del libro di testo

Consider the reaction: I2(g) + Cl2(g) ⇌ 2 ICl(g) Kp = 81.9 at 25 °C Calculate ΔGrxn for the reaction at 25 °C under each of the following conditions: c. PICl = 2.55 atm; PI2 = 0.325 atm; PCl2 = 0.221 atm

2862
views