CHM 1321A
Mid Term 2 Version B Answers
1. Compare the two hydrogens shown in this compound and circle the one that is more acidic. (1 point)
a. Draw the two possible conjugate bases (2 points).
b. Circle the conjugate base in part a that is more stable (1 Point)
c. Briefly justify your answer in part b. Structures may be helpful in your explanation. (5
points)
- Charge is delocalized in this base
- Spreading the charge over more than one atom will lower the energy of the base and make it
more stable
2. Consider the two reacting sites on the following molecule, and how they can react with HCl.
a. Draw the two possible conjugate acids that can be formed from this reaction. (2 points).
b. Underline the weakest acid in part a. (1 Point)
c. Justify your answer in part b (3 Points).
- nitrogen is left of oxygen in the periodic table
- nitrogen is less electronegative than oxygen
- positive charge will be more stable on the less electronegative atom (nitrogen)
d. Using the data from part b, predict the site of protonation on the original molecule and briefly
explain your choice. (2 Points)
- Molecule will react to form the weakest acid
3. Consider the following reaction.
1
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, a) What is the structure of product A and product B? (2 points).
b) Provide a detailed mechanism showing the formation of product A. (5 points).
4. Write a detailed mechanism for this transformation (8 points).
5. Consider the following structure
a) Construct the significant resonance forms for this molecule. (9 points).
b) Label the best resonance form(s) in part a. Provide a brief justification for your choice. (3 points).
- All the atoms in the indicated form have full octets. Each of the other structures has at least one atom
with an incomplete octet
c) Draw the resonance hybrid structure for this molecule. (3 points).
2
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Mid Term 2 Version B Answers
1. Compare the two hydrogens shown in this compound and circle the one that is more acidic. (1 point)
a. Draw the two possible conjugate bases (2 points).
b. Circle the conjugate base in part a that is more stable (1 Point)
c. Briefly justify your answer in part b. Structures may be helpful in your explanation. (5
points)
- Charge is delocalized in this base
- Spreading the charge over more than one atom will lower the energy of the base and make it
more stable
2. Consider the two reacting sites on the following molecule, and how they can react with HCl.
a. Draw the two possible conjugate acids that can be formed from this reaction. (2 points).
b. Underline the weakest acid in part a. (1 Point)
c. Justify your answer in part b (3 Points).
- nitrogen is left of oxygen in the periodic table
- nitrogen is less electronegative than oxygen
- positive charge will be more stable on the less electronegative atom (nitrogen)
d. Using the data from part b, predict the site of protonation on the original molecule and briefly
explain your choice. (2 Points)
- Molecule will react to form the weakest acid
3. Consider the following reaction.
1
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, a) What is the structure of product A and product B? (2 points).
b) Provide a detailed mechanism showing the formation of product A. (5 points).
4. Write a detailed mechanism for this transformation (8 points).
5. Consider the following structure
a) Construct the significant resonance forms for this molecule. (9 points).
b) Label the best resonance form(s) in part a. Provide a brief justification for your choice. (3 points).
- All the atoms in the indicated form have full octets. Each of the other structures has at least one atom
with an incomplete octet
c) Draw the resonance hybrid structure for this molecule. (3 points).
2
This study source was downloaded by 100000858936669 from CourseHero.com on 02-06-2023 05:20:53 GMT -06:00
https://www.coursehero.com/file/36233205/CHM1321-2017-midterm-2-with-answerspdf/
