Pure calcium is stored to prevent it from reacting with air and moisture. Specifically, it's kept in a dark glass container with a tightly closed lid, submerged under a layer of paraffin oil or kerosene.
Why This Storage Method?
Calcium is a highly reactive alkaline earth metal. In its pure form, it readily reacts with:
- Oxygen in the air: This leads to the formation of calcium oxide (CaO).
- Moisture (water vapor) in the air: This results in the formation of calcium hydroxide (Ca(OH)₂).
These reactions tarnish the calcium and degrade its purity. The storage method is designed to prevent these reactions.
Key Elements of the Storage Method:
- Dark Glass Container: Darkness helps to minimize any potential light-induced reactions or degradation, though the primary reason for the dark glass is likely more traditional storage practice.
- Tightly Closed Lid: This is crucial for preventing the entry of both air and moisture. A good seal is essential to maintain the integrity of the calcium.
- Paraffin Oil (or Kerosene) Submersion: The layer of paraffin oil or kerosene acts as a barrier, physically isolating the calcium from the atmosphere. Both liquids are non-reactive with calcium and effectively prevent contact with oxygen and water vapor. They are also relatively inexpensive and readily available.
In Summary
To maintain the purity of calcium, it must be stored in conditions that prevent it from reacting with the surrounding environment. The described storage method is an effective way to achieve this.
