When ferric chloride is added to potassium ferrocyanide there is formation of

Options

A. Prussian blue
B. Nitroprusside ion
C. Coloured ring
D. Ferrous nitrate

Answer

To solve the question regarding the reaction between ferric chloride and potassium ferrocyanide, we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are:
- Ferric chloride (FeCl₃)
- Potassium ferrocyanide (K₄[Fe(CN)₆])

### Step 2: Write the Chemical Equation
When ferric chloride reacts with potassium ferrocyanide, the following reaction occurs:
\[ 3 \text{FeCl}_3 + 2 \text{K}_4[\text{Fe(CN)}_6] \rightarrow 2 \text{K}_3[\text{Fe}_2(\text{CN})_6] + 6 \text{KCl} \]
This reaction produces a complex compound known as potassium di-iron(III) hexacyanoferrate(II), which is often referred to as "Persian blue."

### Step 3: Identify the Product
The product formed from this reaction is:
- Potassium di-iron(III) hexacyanoferrate(II) (K₃[Fe₂(CN)₆])
- A dark blue precipitate known as "Persian blue."

### Step 4: Conclusion
Thus, when ferric chloride is added to potassium ferrocyanide, a dark blue precipitate of Persian blue is formed along with potassium chloride (KCl).

### Final Answer
The formation of a dark blue precipitate known as Persian blue occurs when ferric chloride is added to potassium ferrocyanide.

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