26.3 - Carboxylic acids

Question 1

What does the carboxyl group look like?

Answer 1

Contains hydroxyl and carbonyl

Question 2

Describe the solubility of carboxylic acids.

Answer 2

• Both the carbonyl and hydroxyl are polar so they can H-Bond with water
• Carboxylic acids with up to 4 carbons are soluble in water
  
  • Solubility decreases as chain lenght increases, as non-polar carbon chains affect overall molecule polarity
• Dicarboxylic acids are solid at RT and readily dissolve in water

Question 3

Are carboxylic acids strong or weak

Answer 3

WEAK ACIDS

HCOOH_(aq) ⇔ H⁺_(aq) + HCOO^-_(aq)

partial dissociation

Question 4

What are the acid reactions of carboxylic acids?

Answer 4

Carboxylic acids undergo:

• Redox w/ metals
• Neutralisation w/bases

All result in carboxylic acid → carboxylate salt

(example shown is carboxylic acid + NaOH)

Question 5

Give general reactions for carboxylic acids + metals

Answer 5

carboxylic acid + metal → H₂ + carboxylate salt

example of a carboxylate salt

Question 6

Give general neutralisation reactions for carboxylic acids

Answer 6

+ metal oxides

CA + metal oxide → carboxylate salt + water

+ alkali

CA + alkali → carboxylate salt + water

+ carbonate

CA + CO₃^2- → carboxylate salt + water + carbon dioxide

Question 7

How do you test for carboxyl groups?

Answer 7

Carboxylic acids are the only acids, sufficiently acidic enough to react w/ carboncates, as opposed to phenols which can’t