Confirmatory Tests

Question 1

Sodium carbonate solution/ sodium hydrogen carbonate solution

Answer 1

Carboxylic acid

Effervescence of a colourless gas
Practicals: …that turns lime water milky

Question 2

Potassium iodide solution

Answer 2

Lead(II) ions
A yellow precipitate is formed

Question 3

Potassium dichromate solution
Lead(II) ions

Answer 3

A yellow precipitate is formed
- Precipitate is soluble in dilute nitric acid (forming an orange solution)
- Soluble in dilute sodium hydroxide solution (forming a yellow solution)

Question 4

Acidified potassium permanganate/ potassium manganate (vii)

Answer 4

Unsaturated compounds eg primary alcohols, secondary alcohols, aldehydes, methanoic acid, glucose

Purple solution turns colorless

Question 5

Acidified potassium dichromate (vi)

Answer 5

Unsaturated compounds eg primary alcohols, secondary alcohols, aldehydes, methanoic acid, glucose

Orange solution turns green

Question 6

Iodine solution and dilute sodium hydroxide solution

Question 7

Neutral iron (iii) chloride solution

Answer 7

Phenols
Violet solution formed

Question 8

2,4-dinitrophenolhydrazine (Brady’s reagent)

Answer 8

Carboxyl compounds (aldehydes and ketones)

Orange/ yellow Preciptate formed