Hello aspirant
The angle of contact of Mercury with glass is obtuse.
The angle of contact of water with glass is acute.
When a liquid comes in contact with solid, three surfaces are formed namely liquid-air, solid-air and solid-liquid. The surface tensions corresponding to these interfaces are T
LA
,T
SA
and T
SL
respectively
Now angle of contact of solid with liquid is
θ=
T
−T
In case of mercury-glass T
<T
,making cosθ negative and the angle of contact obtuse.
The angle between the tangent to the liquid surface at the point of contact and the surface inside the liquid is called the angle of contact Θ
Τhe respective interfacial tensions between the liquid-air, solid-air, and solid-liquid interfaces. At the line of contact, the surface forces between the three media must be in equilibrium
Hello candidate,
The angle of contact with liquid's to the solid surface refers to the angle which the upper meniscus of the liquid surface makes with its contact surface such as glass or any other material in which the liquid has been placed.
If we talk about the angle of contact of water with glass the angle is nearly equal to zero degree or a plane meniscus. But if we talk about the angle of contact of Mercury, it comes out to be nearly 135 degrees.
Have a good day.
Question : On a clean glass plate, a drop of water spreads to form a thin layer, whereas a drop of mercury remains almost spherical because:
Option 1: mercury is a metal
Option 2: the density of mercury is greater than that of water
Option 3: the cohesion of mercury is greater than its adhesion with glass
Option 4: the cohesion of water is greater than its adhesion with glass
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