Fe 3 + cation gives a prussian blue precipitate on addition of potassium ferrocyanide solution due to the formation of

Step-by-step solution

Ferric ion forms a prussian blue precipitate due to the formation of F e 4 F e C N 6 3 . In this method, to a portion of sodium fusion extract, freshly prepared ferrous sulphate F e S O 4 solution is added and warmed. Then about 2 to 3 drops of F e C l 3 solution are added and acidified with conc. H C l . The appearance of a prussian blue colour indicates the presence of nitrogen. F e S O 4 + 2 N a O H → F e O H 2 + N a 2 S O 4 6 N a C N + F e ( O H ) 2 → N a 4 [ F e ( C N ) 6 ] Sodium ferrocyanide + 2