What is observed when fused lead bromide is electrolysed using platinum electrodes ?

Options

A. A silver grey deposit at anode , and a reddish brown deposit at cathode .
B. A silver grey deposit at cathode , and a blue deposit at anode .
C. A silver grey deposit at cathode , and a reddish brown vapour brown vapour at anode .
D. A silver grey vapour at cathode , and a reddish brown vapour at anode .

Answer

To solve the question regarding the observations made when fused lead bromide (PbBr2) is electrolyzed using platinum electrodes, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Electrolysis**: Electrolysis is a process that uses an electric current to drive a non-spontaneous chemical reaction. In this case, we are electrolyzing fused lead bromide.

2. **Identifying the Electrodes**: Platinum electrodes are used in this process. These electrodes are inert, meaning they do not participate in the chemical reactions occurring during electrolysis.

3. **Dissociation of Lead Bromide**: When lead bromide is fused, it dissociates into its constituent ions:
- Lead ions (Pb²⁺)
- Bromide ions (Br⁻)

4. **Reactions at the Electrodes**:
- **At the Cathode (Negative Electrode)**: Reduction occurs. The lead ions (Pb²⁺) gain electrons and are reduced to solid lead (Pb):
\[ \text{Pb}^{2+} + 2e^- \rightarrow \text{Pb (s)} \]
This results in a silver-grey deposit of lead at the cathode.

- **At the Anode (Positive Electrode)**: Oxidation occurs. The bromide ions (Br⁻) lose electrons and are oxidized to form bromine gas (Br₂):
\[ 2\text{Br}^- \rightarrow \text{Br}_2 (g) + 2e^- \]
Bromine gas is released at the anode, which appears as reddish-brown vapors.

5. **Final Observations**:
- At the cathode, a silver-grey deposit of lead is observed.
- At the anode, reddish-brown vapors of bromine gas are observed.

### Conclusion:
The correct observation when fused lead bromide is electrolyzed using platinum electrodes is:
- Silver-grey deposit at the cathode.
- Reddish-brown vapors of bromine gas at the anode.

### Answer:
C) Silver-grey deposit at cathode and reddish-brown vapors at anode.

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