Ch.19 - Chemical Thermodynamics

Brown - Chemistry: The Central Science 14th Edition

Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Non è quello che usi tu?Cambia libro di testo

Brown 14th Edition

Ch.19 - Chemical Thermodynamics

Problema 69a

Capitolo 19, Problema 69a

Consider the following reaction between oxides of nitrogen: NO₂(g) + N₂O(g) → 3 NO(g) (a) Use data in Appendix C to predict how ΔG for the reaction varies with increasing temperature.

Guida verificata passo dopo passo

Identify the reaction: NO_2(g) + N_2O(g) \(\rightarrow\) 3 NO(g)

Understand that \(\Delta\) G (Gibbs free energy change) is related to \(\Delta\) H (enthalpy change) and \(\Delta\) S (entropy change) by the equation \(\Delta\) G = \(\Delta\) H - T\(\Delta\) S, where T is the temperature in Kelvin.

Look up the standard enthalpy change (\(\Delta\) H^\(\circ\)) and standard entropy change (\(\Delta\) S^\(\circ\)) for each species involved in the reaction from Appendix C.

Calculate the \(\Delta\) H^\(\circ\)_{reaction} and \(\Delta\) S^\(\circ\)_{reaction} using the formula: \(\Delta\) H^\(\circ\)_{reaction} = \(\sum\) \(\Delta\) H^\(\circ\)_{products} - \(\sum\) \(\Delta\) H^\(\circ\)_{reactants} and \(\Delta\) S^\(\circ\)_{reaction} = \(\sum\) \(\Delta\) S^\(\circ\)_{products} - \(\sum\) \(\Delta\) S^\(\circ\)_{reactants}.

Analyze how \(\Delta\) G changes with temperature: If \(\Delta\) H^\(\circ\) and \(\Delta\) S^\(\circ\) are both positive, \(\Delta\) G will decrease with increasing temperature, making the reaction more spontaneous at higher temperatures. If \(\Delta\) H^\(\circ\) is positive and \(\Delta\) S^\(\circ\) is negative, \(\Delta\) G will increase with temperature, making the reaction less spontaneous.

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:

Concetti chiave

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

Gibbs Free Energy (ΔG)

Gibbs Free Energy (ΔG) is a thermodynamic potential that measures the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure. It is a crucial concept in predicting the spontaneity of a reaction; a negative ΔG indicates a spontaneous process, while a positive ΔG suggests non-spontaneity. Understanding how ΔG changes with temperature is essential for analyzing reaction feasibility.

Video consigliato:

Percorso guidato

01:51

Gibbs Free Energy of Reactions

Temperature Dependence of ΔG

The temperature dependence of Gibbs Free Energy is described by the equation ΔG = ΔH - TΔS, where ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy. As temperature increases, the TΔS term can significantly influence ΔG, potentially making a reaction more or less favorable. This relationship is vital for predicting how ΔG varies with temperature in chemical reactions.

Video consigliato:

Percorso guidato

01:24

Kw Temperature Dependence

Entropy (ΔS)

Entropy (ΔS) is a measure of the disorder or randomness in a system. In chemical reactions, an increase in entropy typically favors spontaneity, as systems tend to evolve towards greater disorder. When analyzing the reaction between nitrogen oxides, understanding the changes in entropy can help predict how the reaction's Gibbs Free Energy will vary with temperature, influencing its spontaneity.

Video consigliato:

Percorso guidato

02:46

Entropy in Thermodynamics

Pratica correlata

Domanda del libro di testo

Methanol (CH₃OH) can be made by the controlled oxidation of methane: CH₄(g) + 12 O₂(g) → CH₃OH(g) (b) Will ΔG for the reaction increase, decrease, or stay unchanged with increasing temperature?

670

views

Domanda del libro di testo

Consider the following reaction between oxides of nitrogen: NO₂(g) + N₂O(g) → 3 NO(g) (b) Calculate ΔG at 800 K, assuming that ΔH° and ΔS° do not change with temperature. Under standard conditions is the reaction spontaneous at 800 K?

654

views

Domanda del libro di testo

Consider the following reaction between oxides of nitrogen: NO₂(g) + N₂O(g) → 3 NO(g) (c) Calculate ΔG at 1000 K. Is the reaction spontaneous under standard conditions at this temperature?

334

views

Domanda del libro di testo

Reactions in which a substance decomposes by losing CO are called decarbonylation reactions. The decarbonylation of acetic acid proceeds according to: CH₃COOH(l) → CH₃OH(g) + CO(g) By using data from Appendix C, calculate the minimum temperature at which this process will be spontaneous under standard conditions. Assume that ΔH° and ΔS° do not vary with temperature.

806

views

Domanda del libro di testo

A certain constant-pressure reaction is barely nonspontaneous at 45 °C. The entropy change for the reaction is 72 J/K. Estimate ΔH.

819

views

Consider the following reaction between oxides of nitrogen: NO2(g) + N2O(g) → 3 NO(g) (a) Use data in Appendix C to predict how ΔG for the reaction varies with increasing temperature.

Risposta video verificata per un problema simile:

Concetti chiave

Gibbs Free Energy (ΔG)

Temperature Dependence of ΔG

Entropy (ΔS)

Consider the following reaction between oxides of nitrogen: NO₂(g) + N₂O(g) → 3 NO(g) (a) Use data in Appendix C to predict how ΔG for the reaction varies with increasing temperature.