Chemical Engineering - Fluid Mechanics - Discussion

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.

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.

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.

Actually, both answer (surface tension, cohesive) are correct because surface tension is caused by cohesive force b/w surface molecules.

Why not cohesion?

It is greater than 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.

Hello friends.

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

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.

Mercury does not wet glass - the cohesive forces within the drops are stronger than the adhesive forces between the drops and glass. When liquid mercury is confined in a tube, its surface (meniscus) has a convex shape because the cohesive forces in liquid mercury tend to draw it into a drop.

It is the cohesion force that predominates in mercury and hence the molecules of mercury tend to remain together as cohesion is attractive force between like particles. Hence the glass surface doesn't get wet.