Chemical Tests to Distinguish CH3CHO and C6H5CH2CHO:

To distinguish between CH3CHO (acetaldehyde) and C6H5CH2CHO (benzaldehyde) chemically, several tests can be performed. Among these tests, the iodoform test is the most suitable to differentiate between these two compounds. Let's discuss the tests in detail:


The iodoform test is a chemical test used to detect the presence of compounds containing the CH3CO group (acetyl group) or compounds that can be oxidized to form this group. This test is based on the reaction of the compound with iodine and sodium hydroxide in the presence of an excess of iodine.

Procedure:
1. Take a small amount of the compound in a test tube.
2. Add a few drops of sodium hydroxide (NaOH) solution to the test tube.
3. Shake the test tube to dissolve the compound.
4. Add a few drops of iodine (I2) solution to the test tube.
5. Mix the contents of the tube well and observe the reaction.


- If the compound contains the CH3CO group, a yellow precipitate of iodoform (CHI3) will form. The iodoform has a distinct yellow color and a characteristic smell.
- If the compound does not contain the CH3CO group, no precipitate will form, and the solution will remain colorless.


In the case of CH3CHO (acetaldehyde), the iodoform test gives a positive result. Acetaldehyde contains the CH3CO group, which reacts with iodine and sodium hydroxide to form iodoform.

On the other hand, C6H5CH2CHO (benzaldehyde) does not contain the CH3CO group. Therefore, it does not react with iodine and sodium hydroxide to form iodoform. Hence, in the iodoform test, benzaldehyde gives a negative result.

Therefore, the iodoform test is the most suitable chemical test to distinguish between CH3CHO and C6H5CH2CHO.