Phosphorus is kept under water to prevent it from reacting with the oxygen in the air.
Phosphorus, particularly white phosphorus, is a highly reactive non-metal. Its reactivity stems from its unstable tetrahedral structure, which readily reacts with oxygen. This reaction is so vigorous that it can lead to spontaneous combustion in air.
To mitigate this hazardous reactivity, phosphorus is stored submerged in water. Water acts as a barrier, preventing the phosphorus from coming into contact with the atmospheric oxygen that fuels its rapid oxidation. This simple yet effective method significantly reduces the risk of fire and ensures safer handling and storage of this important element.
Here's a breakdown of why water is used:
- Prevents Oxidation: Water isolates the phosphorus from the oxygen in the air, halting the oxidation process that leads to combustion.
- Inert Medium: Water is generally inert to phosphorus under normal conditions. It doesn't react with it, maintaining its stability.
- Accessibility: Water is readily available and cost-effective, making it a practical storage solution.
While white phosphorus is the most common type stored under water, other allotropes of phosphorus, like red phosphorus, are less reactive and do not require such stringent storage conditions. However, white phosphorus is primarily the focus when discussing storage in water due to its extreme reactivity.
