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

Question

TestHub · Accepted Answer

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.

$F e S O_{4} + 2 N a O H \to F e {(O H)}_{2} + N a_{2} S O_{4}$

$6 N a C N + F e {(O H)}_{2} \to \underset{Sodium ferrocyanide}{N a_{4} [F e {(C N)}_{6}]} + 2 N a O H$

$3 N a_{4} [F e {(C N)}_{6}] + 4 F e C l_{3} \to \underset{\begin{array}{l} Ferric ferrocyanide \\ (prussian blue) \end{array}}{F e_{4} {[F e {(C N)}_{6}]}_{3}} + 12 N a C l$

Chemistry - Salt Analysis Question with Solution | TestHub

Options:

Doubts & Discussion