What are the Conditions Necessary for Combustion
Conditions Necessary for Combustion
The following conditions are necessary for combustion to take place.
- Presence of a combustible substance: Combustion is only possible if the substance is combustible.
- Presence of a supporter of combustion: Adequate supply of a supporter of combustion (e.g., oxygen) is essential for combustion.
- Attainment of ignition temperature: A substance starts to burn only after it has attained a certain minimum temperature. The temperature at which a particular substance burns in the presence of air is called its ignition temperature. A substance cannot catch fire if its temperature is lower than its ignition temperature.
Substances like alcohol, petrol, LPG, and nylon fibres catch fire very easily. This is because these substances have low ignition temperatures. Such substances are called inflammable substances. Special care needs to be taken while storing or transporting inflammable substances.
Activity
Aim: To prove that combustion of a candle does not take place below its ignition temperature
Materials needed: A lit candle and aluminium foil
Method: Cut a hole in a piece of aluminium foil and slide it just below the base of the candle flame and above the melted wax (figure B).
Observation: The candle is extinguished (figure C).
Conclusion: The candle is extinguished because the aluminium foil conducts away the heat and the temperature goes below the ignition temperature.
Note: Adult supervision required.
