Distinguish Between Aldehyde And Ketone

Question 1

Using Fehling’s solution

Describe a positive test and what does it tell you

Answer 1

1. Mix Fehling’s solution 1 and Fehling’s solution 2 in a test tube
2. Add a few cm^3 of resulting solution to the liquid in a test tube and warm in a water bath

Blue solution changes to give a red precipitate - aldehyde present

Question 2

Using Tollens’ reagent

Describe a positive test and what does it tell you

Answer 2

Mix a few cm^3 of the liquid with ammonia and silver nitrate solution in a test tube and warm in a water bath

Colourless solution changes to give a silver mirror - aldehyde present