Why mercury is not wet?
The wetting tendency of any liquid to the solid surface is known by the contact angle formed between the solid and the liquid drop placed on the solid. This angle is measured through water. In case of mercury the value of this angle comes out to be 180 degree, which signifies completely non wetting behaviour.
The reason for this non wetting behaviour depends upon the surface tension , role of cohesive and adhesive forces and the contact angle.
Because its actually a metal.
beacuse it does not have water it has gas .
It's surface tension is a negative coefficient. So it does not "absorb" into other materials when in liquid form.
When something is "Wet" that usually means it breaks down water tension. Mercury sinks in water and does not mix with it readily. As a result it's not considered "Wet" in that it has no impact upon water tension.
Soap, for example, breaks down water tension making it "wetter."
When we place a liquid drop onto a solid surface we see the drop quickly adopt a flat, spread-out shape (the drop wets the surface), a tall rounded shape (the drop does not wet the surface), or something in between.
Ideally, the shape of a drop of mercury or water (floating in space and in zero gravity) will be perfectly round. In common experience, we see drops that are not perfectly round because of contact with other surfaces (the subject of this question) and gravity (which tends to flatten drops on surfaces).
All of these observations result from the attractive forces – acting kind of like imaginary rubber bands – among the atoms or molecules that make up the liquid and which also exist between the liquid and a solid surface. Because the atoms or molecules at the surface of a liquid do not experience equal attractive forces on all sides, there is a “surface energy” per unit area that is characteristic of the liquid. (Liquid drops tend to be round to minimize this energy.) Equivalently, surface energy is accounted for in breaking apart liquid-liquid attractive forces as a droplet is pulled out from a larger volume of liquid. Liquids which have stronger internal attractive forces will also have a higher surface energy.
In our daily lives, surface energies may seem rather small, being large enough to support the weight of a bug on water, but not our own! However, they are hugely significant in practical ways (such as for washing anything and for determining the adhesion of glue, tape, and paint).
If a liquid wets a flat solid surface, the atoms or molecules of this liquid experience a strong attractive force to the solid surface relative to the attractive forces within the liquid. If a liquid “beads up” on a surface into a tall, rounded shape, the attractive forces within the liquid are strong relative to those between the liquid and the solid surface.
These considerations explain why water will wet a clean glass surface but not a dirty glass surface (water has a weaker attractive force to the “dirt” layer on the glass than to clean glass). Because mercury has a surface energy over 6 times greater than that of water (and thus there is a much greater attractive force between the atoms of mercury than between the molecules of water), mercury does not wet glass.
because it is dry cleaned.
Because its cohesive forces are far greater than its adhesive forces. Basically when you put a drop of it on anything, it would rather ball up and and cling to itself rather than cling to whatever its in contact with. A liquid is "wetter" if its adhesive forces are stronger than its cohesive forces.
The addition of soap to water breaks down the cohesive forces of water and so the ratio of adhesive to cohesive forces increases, making it "wetter".
its the closest planet to the sun
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