Decomposition of Red Phosphorus into White Phosphorus

When one strikes a safety mat, the first step is the conversion of a small amount of red phosphorus into white phosphorus. This reaction occurs due to the friction and pressure applied on the mat during the strike. Let's understand this process in detail:

1. Introduction to Phosphorus:
Phosphorus is a chemical element that exists in several allotropes, including red and white phosphorus. Red phosphorus is a relatively stable and less reactive form, while white phosphorus is highly reactive and can ignite spontaneously in air.

2. Red Phosphorus:
Red phosphorus is a polymeric form of phosphorus that is obtained by heating white phosphorus. It is made up of long chains of phosphorus atoms bonded together. Red phosphorus is not as reactive as white phosphorus and is commonly used in safety matches, fireworks, and other pyrotechnic devices.

3. Conversion of Red Phosphorus into White Phosphorus:
When a safety mat is struck, the friction and pressure applied to the mat cause a small amount of red phosphorus to undergo a conversion into white phosphorus. This conversion is a result of the breaking of the long chains of red phosphorus and the formation of individual white phosphorus molecules.

4. Friction and Pressure:
Friction and pressure play a crucial role in this conversion process. The force applied during the strike breaks the polymeric structure of red phosphorus, allowing it to transform into the more reactive white phosphorus. The increased surface area of white phosphorus enhances its reactivity and makes it more prone to chemical reactions.

5. Significance of White Phosphorus:
White phosphorus is highly reactive and can ignite spontaneously in air. It reacts vigorously with oxygen, forming phosphorus pentoxide. This reactivity is exploited in safety matches, where the friction produced by striking the match head against a rough surface converts a small amount of red phosphorus into white phosphorus. The white phosphorus then reacts with the air, producing heat and initiating the combustion of the matchstick.

Conclusion:
In conclusion, when a safety mat is struck, the initial step involves the conversion of a small amount of red phosphorus into white phosphorus due to the friction and pressure applied during the strike. This conversion increases the reactivity of phosphorus and sets the stage for subsequent chemical reactions, such as the burning of the glue and starch present in the safety mat.