Question

The meniscus of mercury in a glass capillary tube is convex because of

A) the very high density of mercury as compared with water.
B) the low surface tension of mercury
C) the greater attraction of mercury atoms to the glass than to each other.
D) the weaker attraction of mercury atoms to the glass than to each other.
E) electrostatic repulsion between the glass and the mercury.

Answer 1

Answer:

D

Explanation:

Firstly in deciding whether the meniscus of a liquid in a glass capillary tube will be convex or concave, we need to understand 2 forces that are in play here. These are the adhesive and cohesive forces.

The cohesive forces are the forces between the molecules present in the liquid. It can be seen as the force of attraction between the molecules of the liquid

The adhesive forces are the forces between the molecules of the liquid and the molecules of the glass.

The reason why mercury has a convex meniscus is because the cohesive forces between the mercury molecules is greater than the adhesive forces between the molecules of the glass and molecules of mercury.

What we are saying in essence is that the intramolecular force of attraction between mercury molecules is greater than the intermolecular force of attraction between the molecules of the glass and water.

Hence we say mercury does not wet glass as the cohesive forces of attraction are greater than the adhesive attraction forces