Textbook Question
For the following values of ∆H° , ∆S°, and T, tell whether the process would be favored.
(b) ∆H° = +7.34 kcal/mol ; ∆S° = +43 cal/mol•K ; T = 325 K
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Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
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Mullins 1st EditionCh. 5 - Chemical Reaction Analysis: Thermodynamics and KineticsProblem 11d
Mullins 1st EditionCh. 5 - Chemical Reaction Analysis: Thermodynamics and KineticsProblem 11dChapter 4, Problem 11d
For the following values of ∆H° , ∆S°, and T, tell whether the process would be favored.
(d) ∆H° = -8.3 kcal/mol ; ∆S° = -12 cal/mol•K ; T = 298 K
Verified step by step guidance1
Step 1: Recall the Gibbs free energy equation: ΔG = ΔH - TΔS. This equation determines whether a process is thermodynamically favored. A negative ΔG indicates a favored process.
Step 2: Convert all units to be consistent. Here, ΔH° is given in kcal/mol, and ΔS° is given in cal/mol•K. Convert ΔH° to cal/mol by multiplying by 1000: ΔH° = -8.3 kcal/mol × 1000 = -8300 cal/mol.
Step 3: Calculate the TΔS term. Multiply the temperature (T = 298 K) by ΔS° (-12 cal/mol•K): TΔS = 298 × (-12) = -3576 cal/mol.
Step 4: Substitute the values into the Gibbs free energy equation: ΔG = ΔH - TΔS. Using the converted ΔH° (-8300 cal/mol) and calculated TΔS (-3576 cal/mol), plug them into the equation.
Step 5: Analyze the sign of ΔG. If ΔG is negative, the process is thermodynamically favored. If ΔG is positive, the process is not favored. Perform the subtraction ΔG = -8300 - (-3576) and determine the sign of the result.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Gibbs Free Energy
Gibbs Free Energy (G) is a thermodynamic potential that helps predict whether a process will occur spontaneously at constant temperature and pressure. It is calculated using the formula ΔG = ΔH - TΔS, where ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy. A negative ΔG indicates that the process is favored.
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05:02
Breaking down the different terms of the Gibbs Free Energy equation.
Enthalpy (ΔH)
Enthalpy (ΔH) is a measure of the total heat content of a system. A negative ΔH value, such as -8.3 kcal/mol, indicates that the process is exothermic, meaning it releases heat. Exothermic reactions are generally favored because they contribute to a decrease in the system's energy, promoting spontaneity.
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04:38Calculating Enthalpies
Entropy (ΔS)
Entropy (ΔS) is a measure of the disorder or randomness in a system. A negative ΔS value, like -12 cal/mol•K, suggests that the process leads to a decrease in disorder. While processes that increase entropy are favored, a negative ΔS can be offset by a sufficiently negative ΔH at high temperatures, affecting the spontaneity of the reaction.
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Related Practice
Textbook Question
Which of the following carbocations would you expect to undergo rearrangement?
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Textbook Question
At what temperature does the entropy change of a process not contribute to the favorability of a process?
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Textbook Question
For the following values of ∆H° , ∆S°, and T, tell whether the process would be favored.
(c) ∆H° = -21.3 kcal/mol ; AS° = -51 cal/mol•K ; T = 373 K
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Textbook Question
A certain process has ∆H° = 11.7 kcal/mol and AS° = +33cal/mol•K . That is, this reaction has an unfavorable enthalpy but a favorable entropy term. At what temperature will the process be neither favored nor disfavored?
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Textbook Question
For the following values of ∆H° , ∆S°, and T, tell whether the process would be favored.
(a) ∆H° = -15 kcal/mol ; ∆S° = +37 cal/mol•K ; T = 273 K
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