Phosphorus
Explanation
Spontaneous combustion is a phenomenon where a substance unexpectedly bursts into flame without the application of an external heat source (such as a match or lighter). This occurs when a material has an ignition temperature lower than the ambient room temperature, causing it to react exothermically with atmospheric oxygen.
Detailed Analysis
- Phosphorus: Specifically, white phosphorus is a highly reactive non-metal with a very low ignition temperature (approximately 35°C). When exposed to air at room temperature, it undergoes slow oxidation which generates enough heat to reach its ignition point, causing it to catch fire spontaneously. Due to this property, white phosphorus is stored under water to prevent contact with atmospheric oxygen.
- Wood: Wood has a high ignition temperature and requires significant external heating to catch fire.
- Iron: Iron does not burn spontaneously at room temperature. While iron filings can burn vigorously when sprinkled into a flame, a solid piece of iron requires intense heating to oxidize rapidly.
- Wax: Wax requires a heat source to melt and vaporize before it can ignite. Its ignition temperature is well above room temperature.
Key Takeaway
White phosphorus is a non-metal known for undergoing spontaneous combustion in air at room temperature due to its extremely low ignition temperature.