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Boiling Point (and other Phase Changes)
As you know, there is NO TEMPERATURE CHANGE during ANY PHASE CHANGE including boiling, freezing, etc.
Boiling point is the temperature where the vapor pressure = atmospheric pressure in the container.
Boiling point is a function of IMF and MW (molecular weight or molar mass).
- For similar IMF substances, higher MW substances will have higher Boiling Point.
- For similar MW substances, higher IMF substances will have higher Boiling Point.
[Excellent explanation of BP and IMF (Aus-e-tute website)]
REMEMBER:
- Vapor pressure is the pressure exerted by the vapor particles (in the gas phase) above a liquid layer (the system must be closed, in other word, the container is sealed).
- Vapor pressure is directly related to the intermolecular force (IMF) keeping the liquid molecules held together. Therefore, the higher the IMF, the less amount of vapor particles are in the gas phase, and therefore, the lower the vapor pressure.