Detection of Elements by Lassaigne’s Solution(Sodium Extract):
Lassaigne’s solution or sodium fusion extract should be prepared to detect Nitrogen, Sulphur and halogens in the given organic compound.
Why do we prepare Lassaigne’s solution?
Materials Required for Lassaigne’s solution:
Following is the list of materials required for the preparation of lassaigne’s solution.
- Sodium metal
- Distilled water
- Organic compound
- Test tube
- Fusion tube
- China dish
- Wire gauze
- Tripod stand’
- Filter paper
- Glass rod
- Bunsen burner
Lassaigne’s solution Preparation Procedure :
Take a small piece of dry sodium metal in a fusion tube.
Heat the fusion tube gently on the Bunsen burner to melt sodium metal.
Add a small amount of organic compound to a fusion tube.
Heat it first gently & then strongly the tube becomes red hot.
Break this fusion tube into a china dish containing 20cm3 of distilled water.
Mix ,boil & filter the solution .
This filtrate is called Lassaigne’s solution or sodium extract
Then divide the filtrate (Lassaigne’s solution ) into three parts to test the presence of N, S & halogens.
It is based upon the fact that when an organic compound containing nitrogen, sulphur and halogen is strongly heated with metallic sodium, its nitrogen converts to ionic NaCN (sodium cyanide), sulphur to ionic NaS (sodium sulphide) and halogen to ionic NaX (sodium halide) if they are present.
What is the purpose of preparing sodium extract or Lassaigne’s solution?
In elemental analysis, the sodium fusion test, also known as Lassaigne’s test, is used to qualitatively determine the presence of foreign elements, notably halogens, nitrogen, and sulphur, in an organic compound.
Which metal is used in Lassaigne’s test?
In Lassaigne’s test, sodium is utilised due to its electropositive character and to transform covalent form to ionic form. It has a very reactive nature.
Related videos !!
For joining best Chemistry Coaching