(Detection of Functional Group In given Unknown Organic Sample)
It carries 2 marks in CBSE Class 12 Science Practical Term II Examination 2021-22 session
Aim :- To detect the Functional Group In given Unknown Organic Sample.
PHYSICAL PROPERTIES
Colour:- Colourless
State:- Liquid.
Odour:- Specific (Like Nail paint remover )
Observation Table:-
| S N | EXPERIMENT | OBSERVATION | INFERENCE |
|---|---|---|---|
| 1 | The sample + alkaline KMnO4 solution is added drop wise to it. | Pink colour does not disappear. | Unsaturation ( Carbon-carbon double / triple bond) is not present in the sample. |
| 2. | Sample is dissolved in water and dip blue litmus paper in it or add few drops of solution on blue litmus paper with clean dropper. | No change in colour. | – OH (Phenolic) or — COOH ( Carboxylic ) functional group is absent. |
| 3. | The sample is dissolved in water and dip blue litmus paper in it or add few drops of solution on blue litmus paper with clean dropper. | No change in colour. | – NH2 ( Amine ) functional group is absent. |
| 4 | Small amount of the sample + 2,4 DNP solution + shake + (heat if required) | Yellow precipitate appears | Presence of carbonyl ( C=O ) group is confirmed. Means either aldehyde or Ketone may present. |
| 5 | Small amount of the sample +Tollen,s reagent + heat | Silver mirror ( surface of test tube becomes shiny due to deposition of silver on glass surface or black precipitate appear in test tube if silver is unable to form deposited itself on surface of test tube. | Presence of aldehyde ( -CHO ) functional group is confirmed. |
| 6 | Small amount of the sample +Mixture of Fehling solution A and B + heat | Red precipitate appears | Presence of aldehyde ( -CHO ) functional group is confirmed. |
| 7 | Small amount of the sample + Sodium nitropruside solution + add NaOH dropwise | Red colour appears | C=O (Ketone ) functional group is absent. |
Result:- The aldehyde functional group is present in the given unknown organic compound.
CHEMIGOD 