Carboxylic Acids

Question 1

What functional group do carboxylic acids contain?

Answer 1

-COOH (carboxyl group)

The carboxyl group is responsible for the acidic properties of carboxylic acids.

Question 2

How do the names of carboxylic acids end?

Answer 2

‘-oic acid’

This suffix indicates the presence of the carboxyl functional group.

Question 3

List the first four carboxylic acids.

Answer 3

• Methanoic acid (HCOOH)
• Ethanoic acid (CH3COOH)
• Propanoic acid (C2H5COOH)
• Butanoic acid (C3H7COOH)

These acids are the simplest members of the carboxylic acid family.

Question 4

What is a common example of a carboxylic acid?

Answer 4

Ethanoic acid

Ethanoic acid is commonly known as acetic acid and is the main component of vinegar.

Question 5

Describe the structure of the COOH group.

Answer 5

A carbon attached to a double-bonded oxygen (C=O) and a single-bonded hydroxyl (-OH)

This structure allows carboxylic acids to exhibit acidic properties.

Question 6

What is the pH range of carboxylic acids in solution?

Answer 6

Between 2-4

This indicates that they are weak acids.

Question 7

Why are carboxylic acids considered weak acids?

Answer 7

They partially ionise in solution

This means that only some molecules release H+ ions into the solution.

Question 8

What is the relationship between pH and hydrogen ion concentration?

Answer 8

Lower pH = Higher H+ concentration

This relationship is crucial in understanding the strength of acids.

Question 9

Fill in the blank: A change of one pH unit represents a _______ difference in H+ concentration.

Answer 9

10x

This highlights the logarithmic nature of the pH scale.

Question 10

What do carboxylic acids produce when reacted with carbonates?

Answer 10

Carbon dioxide (CO₂), water (H₂O), and a salt.

Question 11

How does the reaction of carboxylic acids with carbonates compare to strong acids?

Answer 11

It is a slower reaction.

Question 12

Provide an example of a reaction between a carboxylic acid and a carbonate.

Answer 12

Ethanoic acid + Calcium carbonate → Calcium ethanoate + CO₂ + H₂O.

Question 13

What is the process called when carboxylic acids react with alcohols?

Answer 13

Esterification.

Question 14

What do carboxylic acids and alcohols form during esterification?

Answer 14

Esters and water.

Question 15

What are the components of the Ester Naming Rule?

Answer 15

First part (prefix) from the alcohol, second part (suffix) from the carboxylic acid.

Question 16

Fill in the blank: Carboxylic acids react with alcohols to form _______.

Answer 16

[esters].

Question 17

List an example of esterification involving methanol and ethanoic acid.

Answer 17

Methanol + Ethanoic acid → Methyl ethanoate + Water.

Question 18

List an example of esterification involving propanol and methanoic acid.

Answer 18

Propanol + Methanoic acid → Propyl methanoate + Water.

Question 19

List an example of esterification involving methanol and propanoic acid.

Answer 19

Methanol + Propanoic acid → Methyl propanoate + Water.

Question 20

List an example of esterification involving butanol and propanoic acid.

Answer 20

Butanol + Propanoic acid → Butyl propanoate + Water.

Question 21

What are some uses of esters?

Answer 21

• Perfumes
• Food flavorings
• Solvents
• Plasticizers

Question 22

True or False: Esters have fruity smells.

Answer 22

True.