Textbook Question
Determine the sign of ΔSsys for each process. a. water boiling
Ch.18 - Free Energy and Thermodynamics
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831
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Table of contents
- Ch.1 - Matter, Measurement & Problem Solving136
- Ch.2 - Atoms & Elements112
- Ch.3 - Molecules, Compounds & Chemical Equations159
- Ch.4 - Chemical Quantities & Aqueous Reactions140
- Ch.5 - Gases118
- Ch.6 - Thermochemistry106
- Ch.7 - Quantum-Mechanical Model of the Atom62
- Ch.8 - Periodic Properties of the Elements103
- Ch.9 - Chemical Bonding I: The Lewis Model104
- Ch.10 - Chemical Bonding II: Molecular Shapes & Valence Bond Theory89
- Ch.11 - Liquids, Solids & Intermolecular Forces73
- Ch.12 - Solids and Modern Material59
- Ch.13 - Solutions110
- Ch.14 - Chemical Kinetics140
- Ch.15 - Chemical Equilibrium78
- Ch.16 - Acids and Bases155
- Ch.17 - Aqueous Ionic Equilibrium176
- Ch.18 - Free Energy and Thermodynamics108
- Ch.19 - Electrochemistry118
- Ch.20 - Radioactivity and Nuclear Chemistry82
- Ch.21 - Organic Chemistry150
Chapter 18, Problem 83b
Determine the sign of ΔSsys for each process. b. water freezing
Verified step by step guidance1
Identify the process: Water freezing is a phase change from liquid to solid.
Recall that entropy (ΔS) is a measure of disorder or randomness in a system.
Understand that in the liquid state, water molecules have more freedom of movement compared to the solid state.
Recognize that when water freezes, the molecules become more ordered as they form a crystalline structure.
Conclude that the entropy of the system decreases, so the sign of ΔS_sys is negative.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Entropy (ΔS)
Entropy, denoted as ΔS, is a measure of the disorder or randomness in a system. In thermodynamics, a positive ΔS indicates an increase in disorder, while a negative ΔS signifies a decrease in disorder. Understanding how entropy changes during a process is crucial for predicting the spontaneity and feasibility of that process.
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Entropy in Thermodynamics
Phase Changes
Phase changes, such as freezing, involve transitions between solid, liquid, and gas states. During freezing, water transitions from a liquid to a solid state, which typically results in a decrease in entropy because the molecules become more ordered in the solid phase. Recognizing how phase changes affect entropy is essential for analyzing thermodynamic processes.
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Second Law of Thermodynamics
The Second Law of Thermodynamics states that the total entropy of an isolated system can never decrease over time. This principle implies that spontaneous processes tend to increase the overall entropy of the universe. When considering processes like water freezing, it is important to evaluate how the entropy of the system and surroundings changes to determine the sign of ΔS.
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Related Practice
Textbook Question
Nitrogen dioxide, a pollutant in the atmosphere, can combine with water to form nitric acid. One of the possible reactions is shown here. Calculate ΔG° and Kp for this reaction at 25 °C and comment on the spontaneity of the reaction. 3 NO2(g) + H2O(l)→ 2 HNO3(aq) + NO(g)
Textbook Question
A reaction has an equilibrium constant of 8.5⨉103 at 298 K. At 755 K, the equilibrium constant is 0.65. Find ΔH°rxn for the reaction.