EXPERINMENT 03
Object
Qualitative analysis of unknown organic compound/s by lassaign tests (Nitrogen).
Reference
- Vogel Arthere, Elementary practical organic chemistry, 2nd edition, 1966, published by CBS publisher, page No. 35
- Agarwal O.P., Practical Organic chemistry, published by Krishna educational publisher, Edition 2014, page no. 24-27.
Requirement
Ignition tube, capillary tube, pipette, test tube, china dish, filter paper, funnel, unknown organic compound (urea)
Theory
The Lassaigne’s test, also known as the sodium fusion test, is a qualitative analysis technique used to detect the presence of nitrogen, sulfur, and halogens in an organic compound.
it utilizes the reactivity of sodium with the elements nitrogen, sulfur, and halogens in organic compounds. When heated with sodium, these elements form water-soluble salts, which are then extracted and tested using specific chemical reactions.
Procedure
Sodium Fusion Test (Lassaigne’s Test)
- Take a small piece of dry sodium metal in a fusion tube and heat it gently till the metalmelts or fuses.
- Add equal quantity of compound to this fused metal [ If he compound is a liquid then add two drops of it with a capillary]
- Heat it gently then strongly till it becomes red hot.
- Plung the red hot tube in 10 ml or ¾ of a test tube of distilled water taken in a porcelain dish,covering it immediately with an asbestos sheet crush the fusion tube completely.
- Carry out more fusion in the similar way. Boil the extract for five minutes reduce the volume to about 5 ml and filter. Perform following test using this filtrate.
- 1 ml of extract + 2-3 drops of NaOH solution to make it alkaline.
- Add a few drops of freshly prepared FeSO4solution ,boil for a few minutes ,cool and acidify it with by adding dil. HCl or dil. H2SO4.
- Blue or green colour solution or Prussian blue coloration.
Inference
If Prussian blue color is present —–à Nitrogen is present
Result:
Qualitative analysis of unknown organic compound/s by lassaign tests (Nitrogen) was done successfully.