A2: Carboxylic acids and esters

Question 1

Solubility of carboxylic acids

Answer 1

C=O and O-H bonds are polar allowing them to form hydrogen bonds with water molecules, however if the carbon chain is more than 4, the non polar carbon chain has more effect, so become insoluble

Question 2

Are carboxylic acids strong or weak acids

Answer 2

Weak

Question 3

Test for the carboxylic acids

Answer 3

Neutralisation with carbonates e.g sodium carbonate
Only common organic compound sufficiently acidic enough to react with carbonates

Question 4

Esterification equation

Answer 4

alcohol + carboxylic acid —> ester + water

Question 5

Ester name when propanoic acid and ethanol react

Answer 5

ethyl propanoate

Question 6

Acid hydrolysis of ester

Answer 6

Ester heated under reflux with dilute (aq) acid
ester + water —> carboxylic acid + alcohol

Question 7

Alkaline hydrolysis

Answer 7

Irreversible, heated under reflux with OH-(aq)
ester + OH- —>Carboxylate ion + alcohol