Boiling Point

[bluemax89]

This is probably a simple one for most of you....

Can someone define the following terms :

1. Boiling point.
2. Bubble point.
3. Saturation temp.
4. Dew point.


Are they all the same thing?

 

[phex]

Please correct if i'm wrong:

boiling point: temperature+pressure at which a liquid evaporates.

bubble point: temperature+pressure at which first vapor bubble forms in a liquid

Saturation Temp: temperature at which a given vapor (pressure and composition) has just not even a single droplet of condensate, but would have, should the temp drop an infinitesimal amount

dew point: temperature+pressure where first droplet of condensate forms in a vapor

 

[25362]

All the definitions herebelow refer to vapour-liquid equilibria. And Phex, you are not wrong. Other sophisticated definitions in chemical engineering parlance (meteorology, electricity, nuclear enginnering, warfare, and many other technical fields excluded) are:

Boiling pt.: The temperature at which the transition from the liquid to the gaseous phase occurs at a given pressure for a pure substance. Mixtures may have a range of boiling points. Also described as the temperature at which the vapour pressure of a liquid equals the external pressure. When the external pressure is 1 Atm. abs. it is called normal boiling point.

Bubble pt.:The temperature at which the first bubble of gas appears in a solution of two or more components (when heated slowly) at a given pressure. It is aka boiling point! It is difficult to calculate when the liquid mixture doesn't behave as an ideal solution.

Saturation temperature (when referring to vapour mixes): It is the temperature at which the partial pressure of any constituent is equal to the maximum possible partial pressure under the prevailing conditions, such that any increase in the amount of that constituent will initiate condensation.

Dew point: the temperature and pressure at which a gas or vapour begins to condense to a liquid (= first droplet of liquid appears).

bluemax89, most of these would mean the same thing if we were speaking of one pure substance. They are not when speaking of mixtures.