Chemical Engineering - Fluid Mechanics - Discussion

Surface tension is also important at the interface between a liquid, a gas, and a solid. For example, a meniscus occurs when the surface of a liquid touches a solid wall, as most readily noticed when a capillary tube is placed in a liquid. Consider a glass capillary tube inserted into a liquid, such as water. The water will rise up the tube to a height, h, because surface tension pulls the surface of the water towards the glass, as shown. The meniscus is the curved surface at the top of the water column.

The contact angle is defined as the angle between the liquid and solid surface, as shown in the sketch. Contact angle depends on both the liquid and the solid. If theta is less than 90°, the liquid is said to "wet" the solid. However, if theta is greater than 90°, the liquid is repelled by the solid, and tries not to "wet" it. For example, water wets glass, but not wax. Mercury does not wet glass.

Water wets glass Mercury does not wet glass.

Hello friends.

According to me it should be surface tension because surface tension is also cause of force of adhesion.

Dear friends,

A/c to me, surface tension is responsible for this case. Cohesion b/w molecules of mercury is greater than adhesion b/w mercury and glass and theta is equal to 128 degree.

Why not cohesion?

It is greater than adhesion.

Because the surface tension is force/length.

Actually both answers, surface tension & cohesive are correct but in the question they asked fluid property not a force that's why the answer is surface tension.

When liquid water is confined in a tube, its surface (meniscus) has a concave shape because water wets the surface and creeps up the side. Mercury does not wet glass - the cohesive forces within the drops are stronger than the adhesive forces between the drops and glass.

Surface tension and viscosity are properties of fluid.

So last two option are eliminated and no question of viscosity because viscosity is resistance to the relative motion of fluid layers so answer is surface tension.

Hello, guys.

My answer is cohesion because of attraction forces acting between same molecule.

Mercury in a glass flask is a good example of the effects of the ratio between cohesive and adhesive forces.

Because of its high cohesion and low adhesion to the glass, mercury does not spread out to cover the top of the flask, and if enough is placed in the flask to cover the bottom, it exhibits a strongly convex meniscus, whereas the meniscus of water is concave.

Mercury will not wet the glass, unlike water and many other liquids, and if the glass is tipped, it will 'roll' around inside.