6. Thermodynamics and Kinetics

For the following acid–base pairs, (vi) draw a reaction coordinate diagram.

(e)

Under certain conditions, the reaction of 0.5 M 1-bromobutane with 1.0 M sodium methoxide forms 1-methoxybutane at a rate of 0.05 mol/L per second. What would be the rate if 0.1 M 1-bromobutane and 2.0 M NaOCH₃ were used?

For the reaction coordinate diagram shown, is the forward or reverse reaction faster?

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.

(c) a slightly endothermic, three-step reaction where the first step is rate-determining

Draw a reaction coordinate diagram for a one step reaction that has the following values of E_a and ∆H. (a) E_a = 9 kcal/mol ; ∆H° = + 4 kcal/mol

The rate constant for a reaction can be increased by ______ the stability of the reactant or by ______ the stability of the transition state.

Given the reaction coordinate diagram for the reaction of A to form G, answer the following questions:

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a. How many intermediates are formed in the reaction?

b. Which letters represent transition states?

c. What is the fastest step in the reaction?

d. Which is more stable: A or G?

e. Does A or E form faster from C?

f. Which is the more stable intermediate?

For the following acid–base pairs, (v) show a mechanism for the reaction; and (vi) draw a reaction coordinate diagram.

(f)

How will the rate of the reaction between bromomethane and hydroxide ion be affected if the following changes in concentration are made?

c. The concentration of the alkyl halide is cut in half and the concentration of the nucleophile is doubled.

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

Draw a reaction-energy diagram for a two-step endothermic reaction with a rate-limiting second step.

When ethyl bromide is added to potassium tert-butoxide, the product is ethyl tert-butyl ether.

CH₃CH₂–Br + (CH₃)₃C–O^–K⁺ → (CH₃)₃C–O–CH₂CH₃ ethyl bromide potassium tert-butoxide ethyl tert-butyl ether

a. What happens to the reaction rate if the concentration of ethyl bromide is doubled?