Tests

Question 1

Test for carboxylic acids

Answer 1

• Add sodium carbonate to the sample.
• effervescence
• gas produced turns limewater cloudy
• a carboxylic acid is present.

Question 2

Test for aldehydes

Answer 2

• -Add Tollen’s reagent and heat.
• -A silver mirror indicates the presence of an aldehyde.

Question 3

Test for acyl chlorides

Answer 3

• -Add water to the sample slowly.
• • If white misty fumes are given off, an acyl chloride is present.
• -Acyl chlorides release chloride ions very readily to give hydrogen chloride gas.

Question 4

Test for amines

Answer 4

• -Add universal indicator to the sample.
• -If it turns blue/purple an amine is present.
• -It will also have a fishy smell.
• Amines are basic.

Question 5

Test for alcohols

Answer 5

• -Alcohols react with carboxylic acids in the presence of sulphuric acid to make esters.
• -Add ethanoic acid to the sample, followed by sulphuric acid and heat.
• • If a the mixture starts smelling sweet and fruity an alcohol was present.

Question 6

Distinguishing tests for primary, secondary and tertiary alcohols

Answer 6

• Primary alcohols can be oxidized to aldehydes.
• Secondary alcohols are oxidized to form ketones.
• Tertiary alcohols cannot be oxidized.
• -Add potassium dichromate and dilute sulphuric acid to the mixture and warm gently.
• -If the mixture goes green a primary or secondary alcohol is present.
• -If it does not go green a tertiary alcohol is present.
• If the mixture does go green, add Tollens reagent to the mixture and heat.
• Silver mirror= 1• alcohol

Question 7

Distinguish acyl chloride from chloroalkane

Answer 7

• Add water
• Acylchloride gives white fumes
• No reaction from chloroalkane