1. Fehling’s experiment
by Federico Malpezzi

2. Fehling’s reagent, formed by an equal quantity of Fehling A and Fehling B, is used to to reduce another substance. Therefore the solutions in which is present glucose, that is a reducing agent, are red dyed.

3. Fehling A is made of cupric sulphate pentahydrate.
Fehling B is made of sodium and potassium tartrate and sodium hydroxide.

4. Oxidation
a chemical element undergoes oxidation when it loses electrons. These electrons are taken from another element which in this way is reduced
Reduction
The reduction is the acquisition of one or more electrons by a chemical species.

5. glucose is oxidized losing electrons.
The electrons are captured by cu ++ (light blue) that reducing to cu + turns red.