Boiling Point: what it is, definition and temperature (water, alcohol, etc.) – Chemistry

What is boiling point

The boiling point is temperature at which a substance in the liquid state passes into the gaseous state. This occurs when the vapor pressure of the substance is equal to the pressure outside the substance.

This means that the boiling point depends on the external pressure. When this pressure is equal to 1 atmosphere (atm), the boiling temperature is called the normal boiling point.

For example, him boiling point of water at 1 atm it is 100 °C. When water is boiled at a pressure of 2 atm the boiling point is 120 ºC. This is the principle of pressure cookers, the water “boils” at a higher temperature and that is why the food cooks in less time.

The boiling point of metals is higher than that of water, while the boiling point of alcohol is lower. Below is a table with the boiling point in centigrade of some substances at atmospheric pressure of 1 atm.

Examples of boiling points

Substance Boiling point Water 100 ºC Acetone 56.5 ºC Hydrochloric acid -85 ºC Ethyl alcohol (ethanol) 78 ºC Isopropyl alcohol (isopropanol) 82.4 ºC Methyl alcohol (methanol) 65 ºC Sodium chloride NaCl 1465 ºC Nitrogen N2 -252 ºC Oxygen O2 -183 ºC Mercury 357 ºC Methane -162 ºC Lead 1740 ºC Silver 2212 ºC

See also: Boiling and Evaporation.

Difference between boiling point and melting point

The boiling point and melting point are temperatures at which a substance passes from one state to another.

In the case of the melting point, it is the transition of a substance from the solid state to the liquid state, while the boiling point is the temperature at which a liquid substance passes into the gaseous state.

The boiling point temperature will always be higher than the melting point, that is, the temperature for a liquid substance to evaporate to its gaseous state will be higher than the temperature for the solid substance to become a liquid.

See also Melting Point and Changes in State of Matter.


Murphy, P. (2007) Teaching Structure-Property Relationships: Investigating Molecular structure and Boiling Point. J.Chemical Education, 84:87-101 DOI:10.1021/ed084p97

Atkins, PW (1999) Physical Chemistry, 6th edn. Omega Editions. Barcelona

How to cite: (08/28/2022). “Boiling point”. In: Available in: https:///punto-de-ebullicion/ Consulted:

Scientific review by Ana Zita Fernandes

Doctor in Biochemistry from the Venezuelan Institute of Scientific Research (IVIC), with a degree in Bioanalysis from the Central University of Venezuela.