"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