Free notes of surface tension

Surface tension.

Intermolecular forces:- The forces of attraction and repulsion between their molecules . These forces ,are called intermolecular .
Their is to forces 1) cohesive force. 2) adhesive force.
Cohesive force:- the force of attraction between 2 molecules of same substance called as cohesion.
Adhesive force:- the force of attraction and repulsion between the two different substance like liquid and solid ,solid with gas etc. is called adhesion.
Range of molecular forces:- The maximum distance between 2 molecules upto which intermolecular forces are effective (also called as short range forces). Distance (10 to the power -9).
Sphere of influence :- an imaginary sphere drawn with given molecule as centre and radius equal to the molecular range .
Surface film :- The layer of surface of liquid whose thickness is about equal to range of molecular attraction.
Surface energy :- when a molecular is taken from the inside to the surface layer work is done against the inward resultant force .the work is stored in the formed of potential energy is a surface energy of the liquid.
The potential energy per unit area of the liquid surface under isothermal condition is called surface energy per unit area.
Potential energy is the greater for molecule at the surface film as compared to a molecules well inside the liquid.
These surface energy :- s.I unit - joules. CGS unit- erg. Dimensions- [L2 M1. T(-2)].
Surface tension :- the force per unit length acting on right angle to the imaginary line drawn on the free surface of on liquid is called as surface tension .
T= F/ L. T=SURFACE TENSION F =FORCE , L= LENGTH UNIT- N/A

ANGLE OF CONTACT :-the angle measures when the line is in the contact with a solid then tangent between the two line on the free surface of liquid and solid at the point of contact measured inside the liquid is called the angle of contact.
The pair who have zero contact angles are :- pure water with clean glass , chloroform with clean glass , organic liquid with clean glass.
Other examples :- ether with clean glass 16 degree, kerosene with clean glass 17 degree, methylene with clean glass 29 degree mercury with clean glass 1400 degree etc
Application of surface tension :- 1) tooth paste spread more freely in the mouth . 2) mosquito eggs floats on surface of water due to surface tension 3) if detergents is added in water the surface tension of resulting detergent solutions become less than water . This increase the area of the contact and cleaning ability of water .
The value of surface tension of liquid at critical temperature is zero.
When there is no force acting on the liquid then shape determine by the surface tension.
When temperatures increases then the surface tension is decreases
In hot water the surface tension is very less.
Resultant radius when the two bubbles of r1 and r2 ,then the resultant is r.
When two drop of mercury are combine then the temperature is increases.
Angle of contact is increases when the increases in temperature.
When the liquid wets the solid completely then the meniscus of the liquid is sufficient long tube is concave. And when the hot liquid wets the solid then the shape is convex in the upward direction.
If the smaller and larger bubble are joined then the air blow from smaller to the larger.
If A Capillary tube dip in water container and B capillary tube dip in soap water mixture container then the B tube has less height of capillary action as compare to the A capillary tube.
Formulae :-
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