Why does mercury form a convex meniscus




















If the cohesive forces between molecules of a liquid are stronger than the adhesive forces between the molecules of a liquid and those of the container then you will see a "convex meniscus. Surface tension, which arises due to the cohesive forces in the liquid, likes to minimize the surface area of the liquid, prefering a spherical shape. Adhesion between the liquid and the container, also known as "wetting", encourages as much liquid as possible to be in contact with the container.

When a convex miniscus starts to form, the initial effect is to decrease the surface between the liquid and the container and increase the surface between the container and the gas by the same amount. Only when the curvature gets large does the area of the liquid-gas surface go up much. So the tradeoff that determines whether the miscus is convex or concave is whether the gas-conatiner surface or the liquid-container surface is more 'costly'.

Some liquids, like mercury, have a convex meniscus because the opposite is true - the molecules of the liquid are more strongly attracted to each other than the walls of the container.

A good example of this shape of meniscus can be seen with mercury in a glass container. Which best explains why the meniscus of mercury in a glass tube is convex? A meniscus is a curve formed on the upper surface of a liquid inside a container.

When water is confined in a glass tube, its meniscus surface has a concave shape because the water wets the glass and creeps up the side of the tube. Figure 6 a and 6 b shows capillary tubes inserted in water and mercury respectively. The concave meniscus formed at the surface of the water column is a result of the adhesive forces being greater than the cohesive forces. For water and most liquids, this is the bottom of the meniscus. Convex meniscus is formed. Besides, why does water form a meniscus in a graduated cylinder?

When cohesive forces are greater than adhesive forces the meniscus is concave, as is the case with glass and water. Water-based fluids like sap, honey, and milk also have a concave meniscus in glass or other wettable containers.. Conversely, a convex meniscus occurs when … You may need to download version 2. Water is a common example of a liquid that forms a concave meniscus. Water meniscus is convex, mercury menisucs is concave A meniscus can go up or down. It all depends on if the molecules of the liquid are more attracted to the outside material or to themselves.

A concave meniscus, which is what you normally will see, occurs when the molecules of the liquid are attracted to those of the container. For pure water and pure silver, the … A common liquid that forms a convex meniscus is liquid mercury. A meniscus can go up or down. Glass is electrically polarizable, and attracts charged objects, so water sticks to glass.

Meniscus and Wetting. Water molecules are attracted to the glass container by capillary action, so they form a concave meniscus. A concave meniscus occurs when the particles of the liquid are more strongly attracted to the container adhesion than to each other cohesion , causing the liquid to climb the walls of the container.

The meniscus of mercury in a glass capillary tube is convex because of A the very high density of mercury as compared with water. The meniscus is an integral part of the diarthrodial knee joint with other tissues including articular cartilage, the coronary, posterior, anterior, cruciate, collateral, lateral and transverse ligaments, the synovium and the fibrous capsule. Similarly one may ask, why does water form a meniscus in a graduated cylinder? Mercury in a glass flask is a good example of the effects of the ratio between cohesive and adhesive forces.

Meniscus existing is because of water's high surface tension. For mercury, take the measurement from the top of the meniscus. It is observed that in water the meniscus in the capillary tube is higher than the meniscus in the beaker.

The shape of the menisci are unrelated to the adhesive and cohesive forces. The triple point on a phase diagram is defined as the temperature and pressure at which all three phases solid, liquid, and gas coexist. It is flat, convex or concave, depending on the solid and liquid surface. It is dependent on intermolecular forces at the interface. A convex meniscus is formed when the particles in the liquid have a stronger attraction to each other force of cohesion than to the material of the container force of adhesion.

If horizontal component of force of cohesion equals force of adhesion, remaining forces are weight of molecule and vertical component of force of cohesion of the molecule 'O'. Every point on the free liquid surface remains perpendicular. This results in the meniscus as flat as shown in b. If force of cohesion is less than the force of adhesion there is net horizontal force along OA outward.

Consequently the resultant of horizontal and vertical forces, acts along OR in outward direction but is perpendicular to the liquid surface at O. Thus, resultant force on all liquid molecules on the free surface, acts perpendicular to the liquid surface as shown in c , giving rise to a concave meniscus. Similarly, if force of cohesion is more than the force of adhesion there is net horizontal inward force. Consequently the resultant of horizontal and vertical forces, acts along OR in inward direction but is perpendicular to the liquid surface at O.

And resultant force on all liquid molecules on the free surface, acts perpendicular to the liquid surface as shown in d , giving rise to a convex meniscus.



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