1. Reaction with Oxygen:
* Sodium metal reacts rapidly with oxygen in the air to form sodium oxide (Na₂O).
* This reaction is highly exothermic, meaning it releases heat.
* The reaction equation is: 4Na + O₂ → 2Na₂O
2. Further Reactions:
* The sodium oxide formed can further react with oxygen to form sodium peroxide (Na₂O₂).
* This reaction is also exothermic.
* The reaction equation is: 2Na₂O + O₂ → 2Na₂O₂
3. Reaction with Water Vapor:
* Air also contains water vapor. Sodium metal reacts with water vapor to form sodium hydroxide (NaOH) and hydrogen gas (H₂).
* This reaction is highly exothermic and can even ignite the hydrogen gas, causing a fire or explosion.
* The reaction equation is: 2Na + 2H₂O → 2NaOH + H₂
4. Formation of a Protective Layer:
* The reaction of sodium metal with air results in the formation of a white, powdery layer on the surface of the sodium.
* This layer is composed of sodium oxide, sodium peroxide, and sodium hydroxide.
* This layer acts as a protective barrier, slowing down the further reaction of sodium with air.
Overall Effect:
* When sodium metal is exposed to air, it reacts rapidly and exothermically, forming a variety of compounds.
* The reaction can be dangerous, especially if the sodium is in a large quantity or if the air is humid.
* To prevent this reaction, sodium metal is usually stored under a layer of mineral oil or kerosene, which prevents it from coming into contact with air.
In summary, the exposure of sodium metal to air results in a series of reactions that produce sodium oxide, sodium peroxide, sodium hydroxide, and hydrogen gas, all of which contribute to the formation of a protective layer on the surface of the sodium.
