If a match is placed on top of a pool of gasoline, the gasoline catches on fire. However, if you spray the gasoline into a fine mist and add heat, it explodes. Explain this phenomenon.

From basic knowledge of chemistry, the rate of chemical reaction is proportional to the exposed surface area.

Combustion of the gasoline is a chemical reaction and obeys this law like all other chemical reaction.

In a pool of gasoline, the exposed surface area is limited to the surface above the pool and hence the chemical reaction (combustion) is moderate.

When the gasoline is sprayed into fine mist (atomized), the exposed surface area is greatly maximized allowed more surface area to be involved in the reaction. This increases the rate of the reaction and hence the reaction becomes so spontaneous that it combusts very rapidly and explodes.

This atomization of gas is used in fuel combustion in the internal combustion engine.