Question

Sodium nitroprusside, when added to an alkaline solution of sulphide ions produces purple colouration due to the formation of :

• A. $Na\left[Fe\right(H_{2}O{)}_{5}NOS]$
• B. $N{a}_4\left[Fe\right(CN{)}_{5}NOS]$
• C. $N{a}_3\left[Fe\right(CN{)}_{5}NOS]$
• D. $N{a}_4\left[Fe\right(H_2{O}_5\left)NOS\right]$

Answer 1

Answer: (B)

$N{a}_4\left[Fe\right(CN{)}_{5}NOS]$

Sodium nitroprusside, when added to an alkaline solution of sulphide ions produces purple colouration due to the formation of sodium thio nitroprusside complex which is purple in colour.

The reaction is as follows:
$N{a}_{2}S+N{a}_2\left[Fe\right(CN{)}_{5}NO]\to N{a}_4[Fe\left(CN{)}_{5}NOS\right]$ (purple coloration)

Option B is correct.