Functional Groups and pKa

Question 1

Name six (6) strong acids

Answer 1

1. Hydrochloric acid, HCl
2. Perchloric acid, HClO4
3. Hydrobromic acid, HBr
4. Hydroiodic acid, HI
5. Sulfuric Acid, H2SO4
6. Nitric acid, HNO3

Question 2

Name six (6) weak acid functional groups

Answer 2

1. Sulfonic acids
2. Carboxylic acids
3. Arylsulfonamides
4. Phenols
5. Imides
6. Thiols

Question 3

What is the estimated pKa range of sulfonic acids?

Answer 3

0-2

Question 4

What is the estimated pKa range of carboxylic acids?

Answer 4

4-5

Question 5

What is the estimated pKa range of arylsulfonamides?

Answer 5

6-9

Question 6

What is the estimated pKa range of phenols?

Answer 6

8-11

Question 7

What is the estimated pKa range of imides?

Answer 7

8-10

Question 8

What is the estimated pKa range of Thiols?

Answer 8

9-11

Question 9

Name five (5) weak base functional groups

Answer 9

1. Guanidines
2. Aliphatic nitrogens
3. Amidines
4. Aromatic amines (Ar-NH2)
5. Aromatic nitrogens (nitrogen part of ring)

Question 10

What is the estimated pKb range of guanidines?

Answer 10

1-2

Question 11

What is the estimated pKb range of aliphatic nitrogens?

Answer 11

3-4

Question 12

What is the estimated pKb range of amidines?

Answer 12

4-5

Question 13

What is the estimated pKb range of aromatic amines?

Answer 13

9-13

Question 14

What is the estimated pKb range of aromatic nitrogens?

Answer 14

10-13

Question 15

Why are alcohols and amides neutral functional groups?

Answer 15

Alcohols (pKa 16-19) and amides (pKb 15-17) are not significantly ionized at pH ranges we limit ourselves to in aqueous systems (0-14).