BackHow will the rate of the reaction between bromomethane and hydroxide ion be affected if the following changes in concentration are made?
a. The concentration of the alkyl halide is not changed and the concentration of the nucleophile is tripled.
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.
Consider the following reaction-energy diagram.
a. Label the reactants and the products. Label the activation energy for the first step and the second step.
b. Is the overall reaction endothermic or exothermic? What is the sign of ΔH°?
c. Which points in the curve correspond to intermediates? Which correspond to transition states?
d. Label the transition state of the rate-limiting step. Does its structure resemble the reactants, the products, or an intermediate?
The reaction of tert-butyl chloride with methanol
is found to follow the rate equation
rate = kr[(CH3)3C—Cl]
a. What is the kinetic order with respect to tert-butyl chloride?
a. Draw an approximate reaction-energy diagram for the acid–base reaction of phenol (see below) with 1-molar aqueous sodium hydroxide solution.
b. On the same diagram, draw an approximate reaction-energy diagram for the acid–base reaction of tert-butyl alcohol (see below) with 1-molar aqueous sodium hydroxide solution.
Under certain conditions, the bromination of cyclohexene follows an unusual rate law:
c. What is the overall kinetic order?
From the Arrhenius equation, predict how
b. increasing the temperature affects the rate constant for a reaction.
Draw a reaction coordinate diagram, making sure to label reactants (R), products (P), intermediates (I), transition states (‡), activation energies ( Ea) , and ∆G°, for each of the following.
(a) an exothermic, one-step reaction
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?
From the Arrhenius equation, predict how
a. increasing the experimental activation energy affects the rate constant for a reaction.
For each of the reaction coordinate diagrams shown, (i) indicate the number of steps in the reaction, (ii) label the intermediates, (iii) identify the rate-determining step, and (iv) tell whether Keq is greater than, less than, or equal to zero.
(a)
When a small piece of platinum is added to a mixture of ethene and hydrogen, the following reaction occurs: Ethene
Doubling the concentration of hydrogen has no effect on the reaction rate. Doubling the concentration of ethene also has no effect.
a. What is the kinetic order of this reaction with respect to ethene? With respect to hydrogen? What is the overall order?
When a small piece of platinum is added to a mixture of ethene and hydrogen, the following reaction occurs:
Doubling the concentration of hydrogen has no effect on the reaction rate. Doubling the concentration of ethene also has no effect.
b. Write the unusual rate equation for this reaction.
c. Explain this strange rate equation, and suggest what one might do to accelerate the reaction.
The alkyl carbocation is estimated to be 15 kcal/mol more stable than the alkenyl carbocation. If this is also the difference in the energies of the transition state leading to each, what is the expected rate difference?
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Draw a reaction coordinate diagram for the following reaction in which C is the most stable and B the least stable of the three species and the transition state going from A to B is more stable than the transition state going from B to C:
a. How many intermediates are there?
b. How many transition states are there?
c. Which step has the greater rate constant in the forward direction?
d. Which step has the greater rate constant in the reverse direction?