Textbook Question
Carbon disulfide 1CS22 is a toxic, highly flammable substance. The following thermodynamic data are available for CS21l2 and CS21g2 at 298 K:
Ch.19 - Chemical Thermodynamics
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement177
- Ch.2 - Atoms, Molecules, and Ions231
- Ch.3 - Chemical Reactions and Reaction Stoichiometry216
- Ch.4 - Reactions in Aqueous Solution189
- Ch.5 - Thermochemistry175
- Ch.6 - Electronic Structure of Atoms168
- Ch.7 - Periodic Properties of the Elements150
- Ch.8 - Basic Concepts of Chemical Bonding177
- Ch.9 - Molecular Geometry and Bonding Theories200
- Ch.10 - Gases179
- Ch.11 - Liquids and Intermolecular Forces113
- Ch.12 - Solids and Modern Materials154
- Ch.13 - Properties of Solutions157
- Ch.14 - Chemical Kinetics199
- Ch.15 - Chemical Equilibrium128
- Ch.16 - Acid-Base Equilibria164
- Ch.17 - Additional Aspects of Aqueous Equilibria163
- Ch.18 - Chemistry of the Environment105
- Ch.19 - Chemical Thermodynamics164
- Ch.20 - Electrochemistry171
- Ch.21 - Nuclear Chemistry122
- Ch.22 - Chemistry of the Nonmetals82
- Ch.23 - Transition Metals and Coordination Chemistry79
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry16
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
Chapter 19, Problem 106
The following processes were all discussed in Chapter 18, “Chemistry of the Environment.” Estimate whether the entropy of the system increases or decreases during each process: (a) photodissociation of O₂(g). (b) formation of ozone from oxygen molecules and oxygen atoms. (c) diffusion of CFCs into the stratosphere. (d) desalination of water by reverse osmosis.
Verified step by step guidance1
Step 1: Understand the concept of entropy. Entropy is a measure of the disorder or randomness in a system. Generally, processes that increase disorder increase entropy, while those that decrease disorder decrease entropy.
Step 2: Analyze process (a) - photodissociation of O₂(g). Photodissociation involves breaking a molecule into smaller parts. Since breaking O₂ into individual oxygen atoms increases the number of particles and disorder, the entropy of the system increases.
Step 3: Analyze process (b) - formation of ozone from oxygen molecules and oxygen atoms. This process involves combining O₂ molecules with O atoms to form O₃. Since this reduces the number of gas particles, the entropy of the system decreases.
Step 4: Analyze process (c) - diffusion of CFCs into the stratosphere. Diffusion is the spreading of particles from an area of high concentration to low concentration, increasing disorder. Therefore, the entropy of the system increases.
Step 5: Analyze process (d) - desalination of water by reverse osmosis. Reverse osmosis involves removing salt from water, which decreases the disorder of the system by separating mixed components, thus decreasing the entropy.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Entropy
Entropy is a measure of the disorder or randomness in a system. In thermodynamics, it quantifies the number of possible arrangements of particles in a system, with higher entropy indicating greater disorder. Understanding how entropy changes during chemical processes helps predict the spontaneity and direction of reactions.
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Photodissociation
Photodissociation is the process by which a chemical compound is broken down into its components by the absorption of light. In the case of O₂(g), this process involves the breaking of the O=O bond, leading to an increase in the number of gas particles, which typically results in an increase in entropy due to greater molecular freedom.
Diffusion
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration, driven by the concentration gradient. This process increases the entropy of a system as particles spread out and occupy a larger volume, leading to a more disordered state. In the context of CFCs diffusing into the stratosphere, this results in an increase in entropy.
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