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Worksheets7 - Reaction Mechanisms: Non-kinetic Methods
Total questions: 22
Worksheet time: 11mins
Name
Class
Date
1.
What are the three stages described in detailed reaction mechanisms?
a)
Before reactants approach each other, while atoms are reacting, after products emerge
b)
Before products emerge, while reactants approach, after atoms react
c)
While atoms are reacting, before products emerge, after reactants approach
d)
After reactants approach, while products emerge, before atoms react
2.
Are reaction mechanisms definitively proven?
a)
Yes, always
b)
No, they become "well-accepted" or "established"
c)
Sometimes, depending on the complexity of the reaction
d)
Only in specific cases with extensive experimental data
3.
What are the two main goals of a proposed reaction mechanism?
a)
To explain the reaction and predict outcomes
b)
To identify reactants and isolate products
c)
To determine the rate law and order of the reaction
d)
To calculate equilibrium constant and free energy
4.
Which is more likely: a unimolecular, bimolecular, or termolecular reaction step?
a)
Termolecular
b)
Bimolecular
c)
Unimolecular
d)
Equally likely
5.
In the reaction H3C-I + HO- -> H3C-OH + I-, what is a key mechanistic question?
a)
When does iodine leave?
b)
What is the overall reaction rate?
c)
What is the pKa of H3C-I?
d)
What is the solvent used?
6.
What must a proposed mechanism account for regarding reaction products?
a)
All products and their relative proportions
b)
Only the major product
c)
Only the desired product
d)
Only the stereochemistry of the products
7.
Why might the identification of products exclude certain proposed mechanisms?
a)
The identified products may not be consistent with the predicted products of a proposed mechanism.
b)
Product identification is irrelevant to mechanism.
c)
Mechanisms are based on reactants, not products.
d)
Product identification only provides information about kinetics.
8.
What factor related to starting materials is crucial to consider when studying reaction mechanisms?
a)
Purity
b)
Cost
c)
Availability
d)
Molar mass
9.
How can yield variations with reaction parameters (temperature, pH, etc.) be useful in mechanistic studies?
a)
They can provide insight into the reaction mechanism and its dependence on these factors.
b)
They only affect the reaction rate, not the mechanism.
c)
They are irrelevant to mechanistic studies.
d)
They only matter for industrial applications.
10.
What effect do peroxides and azo compounds have on free radical reactions?
a)
Catalyze
b)
Inhibit
c)
No effect
d)
Vary depending on the reaction
11.
What is a common use of isotopes like D, 18O, 13C, and 14C in mechanistic studies?
a)
Labeling reactants to track atom movement during the reaction
b)
Increasing reaction rates
c)
Changing the reaction mechanism
d)
Determining the molecular weight of products
12.
What type of analysis can be performed using labeled isotopes?
a)
Mass spectroscopy, NMR, radioactivity measurements
b)
Titration, chromatography, UV-Vis spectroscopy
c)
Melting point determination, boiling point determination, density measurement
d)
None of the above
13.
What information can be obtained from isotopic labeling experiments?
a)
Specific information about bonds broken during the reaction
b)
The overall reaction rate
c)
The equilibrium constant
d)
The pKa of the reactants
14.
What is the purpose of a crossover experiment?
a)
To determine if a reaction involves intermolecular or intramolecular steps
b)
To measure the reaction rate
c)
To determine the equilibrium constant
d)
To identify the solvent effect
15.
What is a limitation of non-kinetic methods?
a)
They may not provide information about the rate-determining step
b)
They always provide definitive proof of a mechanism
c)
They are only applicable to simple reactions
d)
They cannot be used in conjunction with kinetic methods
16.
What are reactive intermediates?
a)
Short-lived species that exist at energy minima during a reaction
b)
Stable products of a reaction
c)
Transition states
d)
Starting materials
17.
How does an intermediate differ from a transition state on a potential energy diagram?
a)
Intermediate: energy minimum; transition state: energy maximum
b)
Intermediate: energy maximum; transition state: energy minimum
c)
Both are energy minima
d)
Both are energy maxima
18.
What is the purpose of trapping intermediates?
a)
To form a stable adduct for characterization
b)
To increase the reaction rate
c)
To change the reaction mechanism
d)
To prevent side reactions
19.
In what methods can be used for the detection of intermediates?
a)
Spectral methods like Raman, ESR, NMR, UV-Vis, IR
b)
Titration, chromatography, calorimetry
c)
Melting point determination, boiling point determination
d)
None of the above
20.
What is an isosbestic point?
a)
A wavelength where absorbance doesn't change during a reaction
b)
A wavelength where absorbance changes the most
c)
A point of maximum absorbance
d)
A point of minimum absorbance
21.
What does CIDNP stand for and what does it detect?
a)
Chemically Induced Dynamic Nuclear Polarization, free radicals
b)
Chemically Induced Dynamic Nuclear Polarization, carbocations
c)
Chemically Induced Dynamic Nuclear Polarization, carbanions
d)
Chemically Induced Dynamic Nuclear Polarization, transition states
22.
What does ESR (EPR) detect?
a)
Free radicals
b)
Carbocations
c)
Carbanions
d)
Transition states
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