Talk:Sodium fusion test

Method

A small amount of the organic compound is added to a melted globule of sodium in a test tube and is heated strongly till it becomes red hot. Then it is boiled in water for some time, cooled, and filtered. The filtrate (sodium extract) contains ionic compounds of sodium as:

${\ce {Na + C + N -> NaCN}}$

${\ce {Na + C + N + S -> NaSCN}}$

${\ce {2Na + S -> Na2S}}$

${\ce {Na + X -> NaX}}$

Test for Nitrogen

The sodium extract is made alkaline by adding ${\ce {NaOH}}$. To this reaction mixture is added freshly prepared FeSO4 solution and boiled for sometimes. The formation of Prussian blue color shows the presence of nitrogen while blood red colour indicates the presence of both nitrogen and sulphur.

${\ce {3NaSCN + Fe3 -> Fe(SCN)3}}$

Test for Halogens

Sodium extract is boiled with concentrated HNO3 followed by the addition of AgNO3 solution which yields a white(Cl)/yellow(Br or I) precipitate if halogen is present.

${\ce {NaX + AgNO3 -> AgX + NaNO3}}$

Test for Phosphorus

Sodium peroxide is added to sodium extract to oxidise phosphorus to sodium phosphate. It is boiled with conc. HNO3 and then ammonium molybdate is added. A yellow precipitate indicates the presence of phosphorus.

Shubhrajit Sadhukhan (talk) 13:31, 4 October 2021 (UTC)