AIM: To test the presence of carbohydrate in the given food sample.
PROCEDURE:
| S. No. | Exepriment | Observation | Inference |
| 1 |
CONC H2SO4 TEST Food sample + concentrated H2SO4. Heat |
Charring occurs with the smell of burnt sugar | Carbohydrate present. |
| OR | |||
| 2 |
MOLISCH’S TEST Food sample + Molisch’sreagent (1% alcoholic solution of α naphthol) + concentrated H2SO4along the sides of the test tube. |
A purple ring is obtained at the junction of the two layers. | Carbohydrate present. |
| OR | |||
| 3 |
BENEDICT’S / FEHLING’S TEST Food sample + Benedict’s reagent/ Fehling’s reagent (A mixture of equal amounts of Fehling’s A and Fehling’s B). Heat. |
A red ppt. is obtained. | Carbohydrate present. |
| OR | |||
| 4 |
TOLLEN’S TEST Food sample + Tollen’s reagent (ammonium silver nitrate solution). Heat on the water bath. |
A silver mirror appears on the walls of the test tube. | Carbohydrate present. |
EQUATIONS: (ON BLANK SIDE USING A PENCIL)
1. CHO(CHOH)4CH2OH (Glucose) + 2Cu2+ + 5OH– → COOH(CHOH)4CH2OH(Gluconic acid) + Cu2O + 3H2O
2. CHO(CHOH)4CH2OH(Glucose) + 2[Ag(NH3)2]+ + 3OH– → COOH(CHOH)4CH2OH(Gluconic acid) + 4NH3 + 2H2O + 2Ag
RESULT: : (ON RULED SIDE ) – The food sample has been tested for carbohydrate.
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