Question

Why does petrol catch fire?

Answer 1

Petrol:

1. Petrol is a hazardous substance.
2. It is a highly flammable liquid that emits a vapor that can easily catch fire if not handled properly and has the potential to cause a serious fire and/or explosion.
3. The intermolecular forces between petrol molecules are so weak that at temperatures as low as -43 °C, the molecules will gain enough heat energy to escape as gas and form a flammable mixture with air.
4. In the presence of an ignition source, this flammable mixture will ignite.

The reaction usually produces heat and light. A full combustion process has the following general equation:

$\mathrm{Fuel}+{\mathrm{O}}_2\to {\mathrm{CO}}_2+{\mathrm{H}}_2\mathrm{O}+\mathrm{Heat}\left(\mathrm{Energy}\right)$

Hence, petrol will catch fire depending on its composition, as well as other factors such as pressure, oxygen content, and mode of ignition.