The reference electrode for mercury mercurous sulfate is the Mercury/Mercurous Sulfate (Hg/Hg2SO4) electrode. This electrode is filled with a saturated potassium sulfate solution (10% w/w) and has a standard electrode potential of 615 mV relative to the Normal Hydrogen Electrode (NHE). It is commonly used in electrochemical measurements due to its stability and well-defined potential. Below, the key aspects of this reference electrode are explained in detail.
Key Points Explained:
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Composition of the Electrode:
- The electrode consists of mercury (Hg) in contact with mercurous sulfate (Hg2SO4).
- The electrolyte used is a saturated potassium sulfate (K2SO4) solution, typically at a concentration of 10% w/w. This solution ensures ionic conductivity and stability.
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Electrode Potential:
- The standard electrode potential for the Hg/Hg2SO4 electrode is 615 mV relative to the Normal Hydrogen Electrode (NHE). This potential is well-defined and reproducible, making it a reliable reference for electrochemical measurements.
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Applications:
- The Hg/Hg2SO4 electrode is widely used in electrochemical experiments, particularly in environments where other reference electrodes (e.g., Ag/AgCl) may not be suitable. It is often employed in sulfate-containing solutions or where chloride ions could interfere.
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Advantages:
- Stability: The electrode maintains a stable potential over time, making it suitable for long-term experiments.
- Reproducibility: The well-defined potential ensures consistent results across multiple measurements.
- Compatibility: It is ideal for use in sulfate-based electrolytes, avoiding issues with chloride contamination.
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Comparison with Other Reference Electrodes:
- Compared to the Silver/Silver Chloride (Ag/AgCl) electrode, the Hg/Hg2SO4 electrode is less affected by chloride ions, making it preferable in certain applications.
- It is also more stable than the Calomel electrode (Hg/Hg2Cl2) in sulfate-rich environments.
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Maintenance and Handling:
- The electrode requires proper storage in a saturated potassium sulfate solution to maintain its performance.
- Regular calibration against a known standard (e.g., NHE) is recommended to ensure accuracy.
By understanding these key points, a purchaser or user can make informed decisions about the suitability of the Hg/Hg2SO4 reference electrode for their specific electrochemical applications.
Summary Table:
| Aspect | Details |
|---|---|
| Composition | Mercury (Hg) in contact with mercurous sulfate (Hg2SO4), saturated K2SO4 solution (10% w/w) |
| Electrode Potential | 615 mV relative to NHE |
| Applications | Used in sulfate-containing solutions, avoids chloride interference |
| Advantages | Stable, reproducible, compatible with sulfate-based electrolytes |
| Comparison | Less affected by chloride ions than Ag/AgCl; more stable than Calomel in sulfate-rich environments |
| Maintenance | Store in saturated K2SO4 solution; regular calibration recommended |
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