Question

the test reaction of nitrogen and halogen inorganic compounds.

Answer 1

Answer:

We can detect cyanide ion and hence, nitrogen ion in the sample by the Prussian blue test. The filtered alkaline solution resulting from the action of water upon the sodium fusion is treated iron (II) sulphate and thus, forms sodium hexacyanoferrate (II).

Upon boiling the alkaline iron (II) salt solution, some iron (III) ions are insensibly produced by the action of air. Now, we add dilute sulphuric acid to dissolve the iron (II) and (III) hydroxides. The hexacyanoferrate (II) reacts with the iron (III) salt, producing iron (III) hexacyanoferrate (II), Prussian blue. A Prussian blue precipitate or colouration indicates that nitrogen is present.

FeSO4 + 6NaCN → Na4[Fe(CN)6] + Na2SO4

3Na4[Fe(CN)6] + 2Fe2(SO4)3 → Fe4[Fe(CN)6]3 + 6Na2SO4