Why the angle of contact of mercury with glass is obtuse?
Answer: The cohesive force between the molecules of mercury is more than the adhesive force between the molecules of mercury and those of glass. Actually,cohesive force and Adhesive forces are the phenomenon due to the surface tension of a liquid. The angle made by the mercury from the glass surface is always obtuse.
What is the angle of contact between water and glass?
0°
For pure water and perfectly clean glass, the angle of contact is 0°. For ordinary water and glass, it lies between 8° and 18°. For pure water and pure silver, the angle of contact is 90°.
What is the value of θ for glass and mercury?
h=2γcosθρgr h = 2 γ cos θ ρ g r ….Capillary Action.
| Interface | Contact angle Θ |
|---|---|
| Mercury–glass | 140º |
| Water–glass | 0º |
| Water–paraffin | 107º |
| Water–silver | 90º |
What is the angle of contact for pure water and mercury?
Water rises to a height of 10 cm in a capillary tube and mercury falls to a depth of √2 cm in the same capillary tube. If the density of mercury is ≈14 g/cm3 and angle of contact is 135∘, the ratio of surface tension for water and mercury is (Angle of contact for water and glass is 0∘).
Why does water spread on glass?
Forces of attraction between a liquid and a solid surface are called adhesive forces. Water wets glass and spreads out on it because the adhesive forces between the liquid and the glass are stronger than the cohesive forces within the water.
What is the angle between pure glass and pure water?
But in case of pure water and clean glass, the angle of contact will be \[{0^ \circ }\]since it is pure and does not have any type of impurities (like salt) dissolved in it.
On what factors angle of contact depends?
The angle of contact depends upon the liquid’s nature and the solid in contact and the medium which exists above the free surface of the liquid. The angle of contact increases with an increase in the temperature of the liquid. The angle of contact decreases on adding soluble impurity to a liquid.
How do you find the angle of contacts?
In the tilting method, the droplet is placed on the substrate which is then gradually tilted. The advancing angle is measured at the front of the droplet just as the droplet starts to move. The receding contact angle is measured at the back of the droplet, at the same time point.
What is the formula of angle of contact?
Water does not rise in it. Rather it falls in the tube by virtue of obtuse angle of contact. If θ is acute angle, i.e. θ<9o°, then liquid meniscus will be concave upwards. If θ is 90°, then liquid meniscus will be plane….Surface Tension:
| Surface Tension | Adhesive Force |
|---|---|
| Angle of Contact | Capillarity |
| Jurin’s Law |
What is the angle of contact for glass and mercury acute or obtuse?
(a) The angle of contact of mercury with glass is obtuse, while that of water with glass is acute. (b) Water on a clean glass surface tends to spread out while mercury on the same surface tends to form drops.
What is the shape when a mercury is placed in a glass vessel?
2 Answers. Mercury metal forms a convex meniscus in glass vessels.