Sept. 23, 2019

Angle of Contact:

Angle of contact between a liquid and a solid is defined as the angle enclosed between the tangents to the liquid surface and the solid surface inside the lipuid, both the tangents being drown at the point of contact of the liquid with the solid.

(i) Its value lies between 00 and 1800

= 00 for pure water and glass, = 80 for tap water and glass, = 900 for water and silver

= 1380 for mercury and glass, = 1600 for water and chromium

(ii) It is particular for a given pair of liquid and solid. And also on surrounding medium.

(iii) It does not depend upon the inclination of the solid in the liquid.

(iv) On increasing the temperature, angle of contact decreases.

(v) Soluble impurities decreases the angle of contact.

(vi) Partially soluble impurities increases the angle of contact.