Description: It is commonly taught in General Chemistry classes that the vapor pressure of a liquid or solid varies directly with temperature, i.e., the higher the temperature of a substance, the higher its vapor pressure. When a liquid is heated it begins to boil as the liquid turns to vapor forming bubbles that literally "push away" the ambient atmosphere above the liquid surface. "Boiling" has occurred. The vapor pressure of the liquid became equal to the ambient pressure, counteracting it or pushing it away. We say the liquid is boiling.
Precise measurements of the temperature when a liquid boils may include other ambient pressures. The normal boiling point is that temperature where the vapor pressure of the liquid equals a standard atmosphere or 760 torr. Of course, as the pressure above a liquid at room temperature is steadily decreased, by, say, an aspirator pump, the liquid boiling point will also decrease, so much so that it will "boil" at room temperature, since that is where its vapor pressure equals the ambient pressure. You can consult books like the CRC Handbook of Chemistry and Physics for lists of organic compounds with vapor pressures at various temperatures to predict where a compound will boil at each applied ambient pressure.
