What Does Boiling Point Mean?
A boiling point is the point at which the temperature and pressure conditions are sufficient for a liquid to transform into a vapor. Adding heat or reducing the ambient pressure beyond this point will cause vapor transformation to occur because the liquid's vapor pressure will then be greater than the ambient pressure being exerted on the liquid.
Corrosionpedia Explains Boiling Point
A boiling point is determined by two main attributes: temperature and ambient pressure. Temperature increases the vapor pressure of the liquid or the force over area, which encourages the liquid to vaporize. The ambient pressure is the pressure being exerted on the liquid. The boiling point of a liquid is reached when the vapor pressure and the ambient pressure equal each other. At that point, a liquid can be boiled by increasing the temperature, decreasing the ambient pressure, or a combination of the two.
The boiling point for one type of liquid is almost always different from another type of liquid. For example, water requires a different pressure and temperature to transform into a vapor than mercury.
The variation among the boiling points of liquids is caused by the bonds and forces among the liquid's molecules. If there are strong intermolecular bonds and forces in one liquid and weaker ones in another, then the liquid with the stronger bonds will require a higher temperature and/or a lower ambient pressure in order for it to reach its boiling point.