Domanda del libro di testo
(a) For a process that occurs at constant temperature, does the change in Gibbs free energy depend on changes in the enthalpy and entropy of the system?
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Ch.19 - Chemical Thermodynamics
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970
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TOC.tableOfContents
- Ch.1 - Introduction: Matter, Energy, and Measurement146
- Ch.2 - Atoms, Molecules, and Ions200
- Ch.3 - Chemical Reactions and Reaction Stoichiometry176
- Ch.4 - Reactions in Aqueous Solution155
- Ch.5 - Thermochemistry126
- Ch.6 - Electronic Structure of Atoms131
- Ch.7 - Periodic Properties of the Elements126
- Ch.8 - Basic Concepts of Chemical Bonding123
- Ch.9 - Molecular Geometry and Bonding Theories143
- Ch.10 - Gases147
- Ch.11 - Liquids and Intermolecular Forces91
- Ch.12 - Solids and Modern Materials122
- Ch.13 - Properties of Solutions126
- Ch.14 - Chemical Kinetics174
- Ch.15 - Chemical Equilibrium101
- Ch.16 - Acid-Base Equilibria139
- Ch.17 - Additional Aspects of Aqueous Equilibria146
- Ch.18 - Chemistry of the Environment72
- Ch.19 - Chemical Thermodynamics129
- Ch.20 - Electrochemistry142
- Ch.21 - Nuclear Chemistry101
- Ch.22 - Chemistry of the Nonmetals68
- Ch.23 - Transition Metals and Coordination Chemistry66
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry10
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Non è quello che usi tu?Cambia libro di testo
Capitolo 19, Problema 49
Ammonium nitrate dissolves spontaneously and endothermally in water at room temperature. What can you deduce about the sign of ΔS for this dissolution process?
Guida verificata passo dopo passo1
Step 1: Understand the process: Ammonium nitrate dissolving in water is a physical process where the solid ammonium nitrate dissociates into its ions in the aqueous solution.
Step 2: Recognize the nature of the process: The dissolution is spontaneous and endothermic, meaning it absorbs heat from the surroundings.
Step 3: Apply the Gibbs Free Energy equation: The spontaneity of a process is determined by the Gibbs Free Energy change (ΔG), where ΔG = ΔH - TΔS. For a process to be spontaneous, ΔG must be negative.
Step 4: Analyze the terms: Since the process is endothermic, ΔH is positive. For ΔG to be negative (spontaneous process), the TΔS term must be large enough to overcome the positive ΔH.
Step 5: Deduce the sign of ΔS: Since TΔS must be positive and large to make ΔG negative, ΔS (change in entropy) must be positive, indicating an increase in disorder as the solid dissolves into ions.
Concetti chiave
Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.
Dissolution Process
The dissolution process involves a solute (in this case, ammonium nitrate) interacting with a solvent (water) to form a solution. This process can be influenced by temperature, pressure, and the nature of the solute and solvent. Understanding how solutes dissolve helps in predicting the thermodynamic behavior of solutions.
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04:20
Spontaneity of Processes
Enthalpy Change (ΔH)
Enthalpy change (ΔH) refers to the heat absorbed or released during a chemical process at constant pressure. In the case of ammonium nitrate, the dissolution is described as endothermic, meaning it absorbs heat from the surroundings. This characteristic influences the overall energy balance of the dissolution process and is crucial for understanding the thermodynamic favorability.
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02:34Enthalpy of Formation
Entropy Change (ΔS)
Entropy change (ΔS) is a measure of the disorder or randomness in a system. A positive ΔS indicates an increase in disorder, while a negative ΔS suggests a decrease. In the context of ammonium nitrate dissolving in water, the spontaneous nature of the process implies that despite being endothermic, the increase in disorder from solute particles dispersing in the solvent leads to a positive ΔS.
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01:46Entropy in Phase Changes
Pratica correlata
Domanda del libro di testo
Cyclopropane and propylene are isomers that both have the formula C3H6. Based on the molecular structures shown, which of these isomers would you expect to have the higher standard molar entropy at 25 °C?
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Domanda del libro di testo
Using S° values from Appendix C, calculate ΔS° values for the following reactions. In each case, account for the sign of ΔS°.
(a) C2H4(g) + H2(g) → C2H6(g)
(b) N2O4(g) → 2 NO2(g)
(c) Be(OH)2(s) → BeO(s) + H2O(g)
(d) 2 CH3OH(g) + 3 O2(g) ⟶ 2 CO2(g) + 4 H2O(g)
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Domanda del libro di testo
(b) For a certain process that occurs at constant T and P, the value of ΔG is positive. Is the process spontaneous?