What is the vapor pressure of a liquid at its normal boiling temperature?

1 Answer
May 8, 2017

The vapour pressure is #1*atm# precisely.


#"The normal boiling point, by definition, is the temperature"# #"at which the vapour pressure of the liquid is equal to ONE"# #"atmosphere, and bubbles of vapour form directly in the liquid."#

And this is the principle behind vacuum distillation. If we reduce the ambient pressure, the vapour pressure of the liquid may become equal to the ambient pressure (that developed by the vacuum pump!) at LOWER temperatures, and thus we may distil a liquid that is involatile at 1 atmosphere. Are you with me?

This is a definition for a 2nd year university student. Such sophistication would not be required of an A-level student.