Discuss Lassigne's test.

Explanation

`to` A small dry sodium piece is taken in a fusion tube and heated gently till the sodium melts.
`to` To this molten sodium a small amount of organic compound is added and heated until it changes red hot.
`to` This red hot tube is plunged in a china dish containing water and this content is boiled, cooled and filtered.
`to` The obtained filtrate is known as Lassaigne.s extract.
`to` This test is used to detect the elements Nitrogen, Sulphur, halogens etc.,
Detection of Nitrogen :
The Lassaigne.s extract is made alkaline by adding few drops of dol. `NaOH_(2)` to this freshly prepared `FeSO_(2)` solution is added and warmed then few drops of FeCl, are added followed by acidification with Conc. `HCI (or) H _(2) SO _(4),A` bluish green colouration indicates the nitrogen.
`Na + C + N to Na CN `
`2 Na CN + Fe SO _(4) to Na _(2) SO _(4) + Fe (CN) _(2)`
`Fe (CN) _(2) + 4 AaCN to Na _(4) [Fe (CN) _(6)]`
`3 Na_(4) [Fe (CN) _(6) ]+ 4 Fe Cl _(3) to Fe _(4) [Fe (CN) _(6) ] _(3) + 12 NaCl`
Prussian blue colouration