Question

Prussian blue is formed when

• A. ferrous sulphate reacts with FeCI$_3$
• B. ferric sulphate reacts with Na$_4[Fe(CN)_6$]
• C. ferrous ammonium sulphate reacts with FeCI$_3$
• D. ammonium sulphate reacts with FeCI$_3$

Answer 1

Answer: (B)

ferric sulphate reacts with Na$_4[Fe(CN)_6$]

Answer 2

When the sodium fusion extract is added with
FeCl$_3$ and then the resulting solution is acidified
with dilute hydrochloric acid, the appearance of
Prussian blue colouration confirms the presence of
nitrogen in the organic compound
Na + C + N $\rightarrow$ NaCN
F eSO$_4 + 2N aC N \, \, \, \rightarrow \, \, \, \, Fe(CN)_2 + Na_2SO_4$
$Fe(CN)_2 + 4N aC N \, \, \, \rightarrow \, \, \, \, Na_4[Fe(CN)_6]$
$3Na_4[Fe(CN)_6] + 4FeCl_3 \, \, \, \rightarrow \, \, \, \, Fe_4[Fe(CN)_6]_3$
\hspace60mm Prussian blue
\hspace67mm + 12NaCl