The Street Chemist - Part 18

Boiling point of a flammable liquid is a physical characteristic that is affected by the temperature of the liquid and atmospheric pressure.The last several Street Chemist presentations have centered around hydrocarbon and hydrocarbon derivative families and their chemical characteristics. Parameters of combustion are actually physical characteristics of chemical compounds. One of the hazards of many of these compounds is flammability. The next series of Street Chemist presentations will focus on the parameters of combustion beginning with the boiling point.

BOILING POINT

Boiling point of a flammable liquid is a physical characteristic that is affected by the temperature of the liquid and atmospheric pressure. Boiling point is defined as "the temperature at which the vapor pressure of a liquid equals the atmospheric pressure of the air." Atmospheric pressure is 14.7 psi at sea level. Liquids naturally want to become gases; it is atmospheric pressure that keeps a liquid from becoming a gas at normal temperatures and pressures.

Atmospheric pressure decreases as altitude increases. The higher the altitude, the lower the boiling point of any given material. For example, water boils at 212