Vapour Pressure & Boiling Point : Notes & Video

"IIT-JEE , JEEmains , NEET , Class-12 , Class-11"

Students Lets understand the topic of Vapour Pressure & Boiling point . Here I am explaining the Topic prior to the important topic "Colligative Properties" .

Vapour pressure may be defined as the pressure exerted by the vapours present above the liquid phase , in equilibrium .

Two pure liquids can  not have similar vapour pressure but two solutions can have same vapour Pressure .

Factors Affecting Vapour Pressure 

(a) Vapour Pressure is directly proportional to the Temperature . More is the temperature higher will be the number of vapours & Higher will be the vapour pressure.

(b) Vapour pressure is inversely proportional to intermolecular force of attraction . More is the force of attraction lower will be the number of vapours & Lesser will be the vapour pressure.

Intermolecular forces of attractions are - (a) H-Bond (b) Vander waal Force of attraction .

Q. Which out of Ethyl Alcohol & Diethyl ether possess higher Vapour Pressure ?

Ans- Diethyl ether , Because ethyl alcohol possess Hydrogen Bond .

Q. Which out of Diethyl ether & Diethyl ether possess higher Vapour Pressure ?

Ans - Diethyl ether , due to high Vander waal force of attraction .

 

Boiling Point

It is the temperature at which vapour pressure of liquid become equal to atmospheric Pressure.

Two Pure liquid can not have same boiling point .

Factors affecting Boiling Point

(a)  Boiling point is directly proportional to the Intermolecular force of attraction .

(b) Boiling point decreases with rise in atmospheric pressure.

Note : Following is the  detailed Video class on this topic

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