Why is Sodium Kept Immersed in Kerosene Oil?

Sodium is a Group 1 Alkali Metal and the most reactive metal commonly encountered in the lab. It reacts violently with:

1. Oxygen in Air: 4Na + O₂ → 2Na₂O (Sodium Oxide)

Sodium oxidizes so rapidly in air that a freshly cut surface turns dull within seconds.

2. Water Vapour in Air: 2Na + 2H₂O → 2NaOH + H₂↑ + Heat

Sodium reacts with even the tiny moisture in air, releasing hydrogen gas and enormous heat — enough to ignite the hydrogen and cause a fire or explosion.

Kerosene oil is the ideal protective medium because it satisfies three requirements:

1. It does not react with sodium: Kerosene is a hydrocarbon mixture — chemically inert towards sodium.
2. It is denser than sodium: Sodium floats on water, but kerosene has almost the same density as sodium (~0.8 g/cm³), so sodium sinks and stays completely submerged.
3. It creates a complete barrier: By surrounding the sodium on all sides, kerosene prevents any contact with air (O₂) or moisture (H₂O).

• Potassium (K): Even more reactive than sodium — also stored in kerosene
• Lithium (Li): Slightly less reactive — stored under mineral oil or in sealed containers with inert gas
• Phosphorus (White): Stored under water (reacts violently with air but not water)