Domanda del libro di testo
How does the molar entropy of a substance change with increasing temperature?
889
views
Ch.19 - Free Energy & Thermodynamics
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217
Non è quello che usi tu?Cambia libro di testoScegli un libro di testo diverso
TOC.tableOfContents
- Ch.1 - Matter, Measurement & Problem Solving118
- Ch.2 - Atoms & Elements106
- Ch.3 - Molecules and Compounds131
- Ch.4 - Chemical Reactions and Chemical Quantities56
- Ch.5 - Introduction to Solutions and Aqueous Solutions82
- Ch.6 - Gases114
- Ch.7 - Thermochemistry96
- Ch.8 - The Quantum-Mechanical Model of the Atom60
- Ch.9 - Periodic Properties of the Elements90
- Ch.10 - Chemical Bonding I: The Lewis Model89
- Ch.11 - Chemical Bonding II: Molecular Shapes, VSEPR & MO Theory85
- Ch.12 - Liquids, Solids & Intermolecular Forces51
- Ch.13 - Solids & Modern Materials47
- Ch.14 - Solutions90
- Ch.15 - Chemical Kinetics115
- Ch.16 - Chemical Equilibrium68
- Ch.17 - Acids and Bases136
- Ch.18 - Aqueous Ionic Equilibrium153
- Ch.19 - Free Energy & Thermodynamics93
- Ch.20 - Electrochemistry106
- Ch.21 - Radioactivity & Nuclear Chemistry74
- Ch.22 - Organic Chemistry140
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217Non è quello che usi tu?Cambia libro di testo
Capitolo 19, Problema 50d
Predict the conditions (high temperature, low temperature, all temperatures, or no temperatures) under which each reaction is spontaneous. a. H2O(g) → H2O(l) b. CO2(s) → CO2(g) c. H2(g) → 2 H(g) d. 2 NO2(g) → 2 NO(g) + O2(g) (endothermic)
Guida verificata passo dopo passo1
Identify the sign of the enthalpy change (\(\Delta H\)) for the reaction. Since the reaction is described as endothermic, \(\Delta H\) is positive.
Consider the entropy change (\(\Delta S\)) of the reaction. Since the reaction involves the decomposition of two moles of NO2 into three moles of gas (2 NO and 1 O2), the entropy increases, making \(\Delta S\) positive.
Use the Gibbs free energy equation, \(\Delta G = \Delta H - T\Delta S\), to analyze the spontaneity of the reaction. Here, \(T\) represents the temperature in Kelvin.
Since both \(\Delta H\) and \(\Delta S\) are positive, the sign of \(\Delta G\) depends on the relative magnitudes of \(\Delta H\) and \(T\Delta S\). As temperature increases, \(T\Delta S\) becomes more significant.
Conclude that the reaction is spontaneous at high temperatures where \(T\Delta S\) outweighs \(\Delta H\), making \(\Delta G\) negative.
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:
2mConcetti chiave
Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.
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 (ΔG) is negative. The relationship between enthalpy (ΔH), entropy (ΔS), and temperature (T) is given by the equation ΔG = ΔH - TΔS, where a negative ΔG indicates a spontaneous process.
Video consigliato:
Percorso guidato
01:51
Gibbs Free Energy of Reactions
Endothermic Reactions
Endothermic reactions absorb heat from their surroundings, resulting in a positive change in enthalpy (ΔH > 0). For such reactions to be spontaneous, the increase in entropy (ΔS) must be sufficiently large to overcome the positive ΔH when multiplied by the temperature (T). This means that at higher temperatures, the entropy term becomes more significant, potentially making the reaction spontaneous.
Video consigliato:
Percorso guidato
02:30Endothermic & Exothermic Reactions
Entropy and Temperature
Entropy (S) is a measure of the disorder or randomness in a system. In the context of chemical reactions, an increase in entropy (ΔS > 0) favors spontaneity. For endothermic reactions, higher temperatures can enhance the impact of entropy on Gibbs Free Energy, making it more likely for the reaction to be spontaneous as temperature increases, thus favoring the formation of products.
Video consigliato:
Percorso guidato
02:35Entropy and Physical Changes
Pratica correlata
Domanda del libro di testo
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S°) at 25 °C. Explain your choices. a. CO(g); CO2(g) b. CH3OH(l); CH3OH(g) c. Ar(g); CO2(g) d. CH4(g); SiH4(g) e. NO2(g); CH3CH2CH3(g) f. NaBr(s); NaBr(aq)
1639
views
Domanda del libro di testo
Calculate the change in Gibbs free energy for each of the sets of ΔH°rxn, ΔS°rxn, and T given in Problem 44. Predict whether or not each reaction is spontaneous at the temperature indicated. (Assume that all reactants and products are in their standard states.)
Domanda del libro di testo
Rank each set of substances in order of increasing standard molar entropy (S°). Explain your reasoning. a. NH3(g); Ne(g); SO2(g); CH3CH2OH(g); He(g) c. CH4(g); CF4(g); CCl4(g)
2273
views
2
rank
Domanda del libro di testo
Calculate the free energy change for this reaction at 25 °C. Is the reaction spontaneous? (Assume that all reactants and products are in their standard states.) 2 Ca(s) + O2( g) → 2 CaO(s) ΔH°rxn = -1269.8 kJ; ΔS°rxn = -364.6 J/K
4891
views
1
rank
Domanda del libro di testo
Fill in the blanks in the table. Both ΔH and ΔS refer to the system.
808
views