(START WRITING IN RHS and continue writing using both sides LHS and RHS )
EXPERIMENT 10 To test the presence of aldehyde Date:
Aim:-
To analyse the given organic compound and identify and confirm the functional group present in it
Sl. No. | EXPERIMENT | OBSERVATION | INFERENCE |
PRELIMINARY TESTS |
1. | Colour noted | No characteristic colour | Absence of phenol and aniline |
2.
| odour noted | Bitter almond odour
| May be aldehyde |
3. | Test with litmus paper: A little of the substance is placed on moist litmus paper | No colour change is noted
| Absence of carboxylic acid, phenol and amine |
TEST FOR ALIPHATIC OR AROMATIC |
1. | A little of the substance is taken in a nickel spatula and shown to flame.
| Burnt with a non-smoky flame
| Presence of Aliphatic substance
|
TEST FOR UNSATURATION |
1. | Test with bromine water: Take small amount of the organic compound in a test tube add 2 ml of distilled water to dissolve it. To this solution add few drops of bromine water and shake it well. | No decolourisation.
| Substance is saturated. |
TEST FOR CARBONYL GROUP – CAN BE EITHER ALDEHYDE OR KETONE |
1. | 2,4-DINITROPHENYL HYDRAZINE TEST (2,4-DNP TEST) Take 0.5ml of the given compound in a clean dry test tube, add a few drops of 2,4-dinitrophenyl hydrazine solution. Shake the mixture and allow to stand. | Formation of yellow or orange crystals
| Presence of carbonyl group that is –CO- group
|
Chemistry :-  |
IDENTIFICATION TEST FOR ALDEHYDES
|
1. | Schiff s test :-Dissolve about 0.5ml or 0.5g of the given compound in alcohol in a clean test tube and add 1ml of Schiff s reagent. Shake and note the change in colour. | Appearance of pink, red or majenta colour
No characteristic reaction | presence of aldehydic group
Absence of aldehyde group |
CONFIRMATORY TEST FOR ALDEHYDES |
1. | TOLLEN S TEST ( SILVER MIRROR TEST) To 1ml of Tollens reagent in a clean test tube, add 3-4 drops of the given liquid and warm the test tube on a water bath for about 5 minutes. | A shining mirror on the walls of the test tube is produced
| presence of aldehyde group confirmed
|
Chemistry 
|
2. | FEHLINGS TEST:-Take 1ml each of Fehling s solurion A and B in a test tube. Add 4-5 drops of the given organic compound and warm the test tube on a water bath for about 5minutes | Reddish precipitate
| presence of aldehyde group confirmed
|
Chemistry 
|
3. | Iodoform test for ethanal Take 1ml of organic compound in a test tube and add about 1ml of 1% iodine solution and add dil. NaOH dropwise until the brown colour of iodine discharged. Warm in water bath | Formation of yellow precipitate | Presence of ethanal which contains CH3CO- group |
Chemistry 
|
RESULT: The given organic compound is identified and confirmed as
Aliphatic saturated aldehyde (ethanal or acetaldehyde)
