Which electrolyte is used in Dennis method for the prepartion of fluorine ?

Options

A. `KHF_2` in anhydrous HF
B. molten cryolite
C. pure dry molten `KHF_2`
D. none of these

Answer

To determine which electrolyte is used in the Dennis method for the preparation of fluorine, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Dennis Method**: The Dennis method is a technique used for the electrolysis of specific compounds to produce fluorine gas. It involves the use of an electrolyte that can facilitate the electrochemical reactions necessary for fluorine production.

2. **Identify Possible Electrolytes**: The question provides several options for the electrolyte:
- KF2 (Potassium Fluoride)
- Anhydrous HF (Hydrofluoric Acid)
- Molten Chloride
- Pure Dry Molten KHF2 (Potassium Hydrogen Fluoride)
- KHF2 (Potassium Hydrogen Fluoride)
- None of these

3. **Determine the Correct Electrolyte**: In the Dennis method, the key electrolyte used is **KHF2 (Potassium Hydrogen Fluoride)**. This compound is used in an anhydrous state along with anhydrous HF at a temperature of around 523 Kelvin.

4. **Electrolysis Process**: During the electrolysis:
- At the cathode, hydrogen gas (H2) is produced.
- At the anode, fluorine gas (F2) is produced.

5. **Conclusion**: Based on the information gathered, the correct electrolyte used in the Dennis method for the preparation of fluorine is **KHF2**.

### Final Answer:
The electrolyte used in the Dennis method for the preparation of fluorine is **KHF2 (Potassium Hydrogen Fluoride)**.

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