Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

6. Thermodynamics and Kinetics

Energy Diagram

Organic Chemistry

6. Thermodynamics and Kinetics

Energy Diagram

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1:39 minutes

Problem 35

Textbook Question

Draw a reaction coordinate diagram for a two-step reaction in which the first step is endergonic, the second step is exergonic, and the overall reaction is endergonic. Label the reactants, products, intermediates, and transition states.

Verified step by step guidance

Start by understanding the reaction coordinate diagram: It is a graph where the x-axis represents the reaction progress (from reactants to products) and the y-axis represents the potential energy of the system. The diagram visually represents the energy changes during the reaction.

Identify the key features of the reaction: Since the first step is endergonic, it means the energy of the intermediate formed after the first step is higher than the energy of the reactants. The second step is exergonic, meaning the energy of the products formed in this step is lower than the intermediate. However, the overall reaction is endergonic, so the energy of the products is higher than the reactants.

Draw the reactants at a lower energy level on the left side of the diagram. Then, draw the first transition state as a peak higher than the reactants, representing the energy barrier for the first step. After the peak, draw the intermediate at a higher energy level than the reactants, as the first step is endergonic.

For the second step, draw the second transition state as another peak, but this time lower than the first transition state, representing the energy barrier for the exergonic step. After the second peak, draw the products at a higher energy level than the reactants but lower than the intermediate, as the overall reaction is endergonic.

Label all components clearly: Mark the reactants, products, intermediates, and transition states on the diagram. Ensure the energy levels and peaks are consistent with the energy changes described (endergonic and exergonic steps).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Reaction Coordinate Diagram

A reaction coordinate diagram visually represents the energy changes during a chemical reaction. The x-axis typically shows the progress of the reaction, while the y-axis indicates the energy level. Key features include reactants, products, intermediates, and transition states, which help illustrate the energy barriers and overall energy changes throughout the reaction.

Endergonic and Exergonic Reactions

Endergonic reactions require an input of energy to proceed, resulting in products that have higher energy than the reactants. In contrast, exergonic reactions release energy, leading to products with lower energy than the reactants. Understanding these concepts is crucial for analyzing the energy profile of a reaction and determining its spontaneity based on Gibbs free energy changes.

Transition States and Intermediates

Transition states are high-energy, unstable configurations that occur during the transformation from reactants to products. They represent the peak of the energy barrier that must be overcome for a reaction to proceed. Intermediates, on the other hand, are more stable species formed during the reaction that exist between the transition states. Identifying these elements is essential for constructing an accurate reaction coordinate diagram.

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Related Practice

Textbook Question

Draw a reaction coordinate diagram, making sure to label reactants (R), products (P), intermediates (I), transition states (‡), activation energies ( E_a) , and ∆G°, for each of the following.

(b) an exothermic, two-step reaction where the second step is rate-determining

Textbook Question

Draw a reaction coordinate diagram, making sure to label reactants (R), products (P), intermediates (I), transition states (‡), activation energies ( E_a) , and ∆G°, for each of the following.

Textbook Question

Draw a reaction-energy diagram for the propagation steps of the free-radical addition of HBr to isobutylene. Draw curves representing the reactions leading to both the Markovnikov and the anti-Markovnikov products. Compare the values of ∆Gº and Ea and for the rate-limiting steps, and explain why only one of these products is observed.

Textbook Question

Draw a reaction coordinate diagram for a reaction in which

a. the product is thermodynamically unstable and kinetically unstable.

b. the product is thermodynamically unstable and kinetically stable.

Textbook Question

The acid dissociation constant (K_a) for loss of a proton from cyclohexanol is 1 × 10^–16.

a. Draw a reaction coordinate diagram for loss of a proton from cyclohexanol.

Textbook Question

The reaction of tert-butyl chloride with methanol

is found to follow the rate equation

rate = k_r[(CH₃)₃C—Cl]

b. What is the kinetic order with respect to methanol?

Textbook Question

Under certain conditions, the bromination of cyclohexene follows an unusual rate law:

c. What is the overall kinetic order?

Textbook Question

The following reaction is a common synthesis used in the organic chemistry laboratory course.

When we double the concentration of methoxide ion (CH₃O^–), we find that the reaction rate doubles. When we triple the concentration of 1-bromobutane, we find that the reaction rate triples.

a. What is the order of this reaction with respect to 1-bromobutane? What is the order with respect to methoxide ion? Write the rate equation for this reaction. What is the overall order?

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