Domanda del libro di testo
Consider a reaction A2(𝑔) + B2(𝑔) ⇌ 2 AB(𝑔), atoms of A shown in red in the diagram and atoms of B shown in blue. (a) If 𝐾𝑐 = 1, which box represents the system at equilibrium?
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Ch.19 - Chemical Thermodynamics
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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TOC.tableOfContents
- 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: 9780134414232Non è quello che usi tu?Cambia libro di testo
Capitolo 19, Problema 8
Using data from Appendix C, write the equilibrium-constant expression and calculate the value of the equilibrium constant and the free-energy change for these reactions at 298 K: (b) 2 HBr(g) + Cl2(g) ⇌ 2 HCl(g) + Br2(g) (c) 2 SO2(g) + O2(g) ⇌ 2 SO3(g)
Guida verificata passo dopo passo1
Step 1: Write the equilibrium-constant expression for each reaction. For a general reaction aA + bB ⇌ cC + dD, the equilibrium constant expression Kc is given by \( K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b} \). Apply this to each reaction.
Step 2: For reaction (b) 2 HBr(g) + Cl2(g) ⇌ 2 HCl(g) + Br2(g), the equilibrium-constant expression is \( K_c = \frac{[HCl]^2[Br_2]}{[HBr]^2[Cl_2]} \).
Step 3: For reaction (c) 2 SO2(g) + O2(g) ⇌ 2 SO3(g), the equilibrium-constant expression is \( K_c = \frac{[SO_3]^2}{[SO_2]^2[O_2]} \).
Step 4: Use the standard Gibbs free energy change equation \( \Delta G^\circ = -RT \ln K \) to relate the equilibrium constant to the free energy change. Here, R is the gas constant (8.314 J/mol·K) and T is the temperature in Kelvin (298 K).
Step 5: Calculate \( \Delta G^\circ \) for each reaction using \( \Delta G^\circ = \sum \Delta G^\circ_{\text{products}} - \sum \Delta G^\circ_{\text{reactants}} \) with values from Appendix C, then solve for K using \( K = e^{-\Delta G^\circ / RT} \).
Concetti chiave
Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.
Equilibrium Constant (K)
The equilibrium constant (K) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. It is derived from the balanced chemical equation and is calculated using the formula K = [products]^[coefficients] / [reactants]^[coefficients]. A large K value indicates that products are favored at equilibrium, while a small K value suggests that reactants are favored.
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01:14
Equilibrium Constant K
Gibbs Free Energy (ΔG)
Gibbs free energy (ΔG) is a thermodynamic quantity that indicates the spontaneity of a reaction at constant temperature and pressure. It is calculated using the equation ΔG = ΔG° + RT ln(Q), where ΔG° is the standard free energy change, R is the universal gas constant, T is the temperature in Kelvin, and Q is the reaction quotient. A negative ΔG indicates a spontaneous reaction, while a positive ΔG suggests non-spontaneity.
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01:51Gibbs Free Energy of Reactions
Reaction Quotient (Q)
The reaction quotient (Q) is a measure of the relative concentrations of products and reactants at any point in a reaction, not necessarily at equilibrium. It is calculated similarly to the equilibrium constant but uses the current concentrations instead of equilibrium concentrations. Comparing Q to K helps predict the direction in which a reaction will proceed to reach equilibrium: if Q < K, the reaction will shift to the right (toward products), and if Q > K, it will shift to the left (toward reactants).
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00:49Reaction Quotient Q
Pratica correlata
Domanda del libro di testo
The accompanying diagram shows how ΔH (red line) and TΔS (blue line) change with temperature for a hypothetical reaction.
(b) In what temperature range is this reaction spontaneous?
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Domanda del libro di testo
Consider a reaction A2(𝑔) + B2(𝑔) ⇌ 2 AB(𝑔), atoms of A shown in red in the diagram and atoms of B shown in blue. (b) If 𝐾𝑐 = 1, which box represents the system at 𝑄 < 𝐾𝑐?
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Domanda del libro di testo
Isomers are molecules that have the same chemical formula but different arrangements of atoms, as shown here for two isomers of pentane, C5H12.
(b) Which isomer do you expect to have the higher standard molar entropy? Explain.
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