Question

Phosphorus is stored in :

• A. Water
• B. Kept open air
• C. Alcohol
• D. Kerosene

Hint:

Do not confuse the storage of reactive metals with reactive non-metals:
- Sodium/Potassium (Highly reactive metals) \(\to\) Stored in Kerosene (react violently with water).
- White Phosphorus (Highly reactive non-metal) \(\to\) Stored in Water (reacts violently with air).

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the safe liquid medium used to store reactive elemental phosphorus in laboratory settings.

Step 2: Key Formula or Approach:
Determine the chemical reactivity of phosphorus (particularly white phosphorus) with atmospheric oxygen and water.

Step 3: Detailed Explanation:

• White phosphorus is a highly reactive non-metal allotrope of phosphorus.

• It has a very low ignition temperature of about \(35^\circ\text{C}\) (\(308\text{ K}\)), which is close to normal room temperature.

• When exposed to air, it reacts spontaneously and vigorously with atmospheric oxygen to undergo rapid combustion, producing dense white fumes of phosphorus pentoxide:
\[ P_4\text{(s)} + 5O_2\text{(g)} \to P_4O_{10}\text{(s)} \] - This reaction is highly exothermic and safety-hazardous.

• To prevent white phosphorus from coming into contact with atmospheric oxygen, it must be isolated from air.

• Because phosphorus does not react with water and is completely insoluble in it, it is safely stored submerged under water.

• (Note: Sodium and potassium are stored in kerosene because they react violently with water. In contrast, phosphorus does not react with water, so water is its ideal storage medium).


Step 4: Final Answer:
Phosphorus is stored in water.