Question

Which of the following explains the formation of the curved surface of water in the graduated cylinder shown below?

Answer 1

Answer: option D, Attractive forces form between polar water molecules and polar glass molecules in the cylinder.

Explanation:

1) The curved surface of water in the cylinder shown in the figure is named concave meniscus.

2) The situation shown reflects two forces that oppose each other.

These are the adhesive force and the cohesiive force.

3) The adhesive force is the of attraction between molecules of different substances, while the cohesive force is the attraction between molecules of the same substance.

4) Water has a strong cohesive force property in virtue of the hydrogen bonds (the particles of water tends to remain together due to the high intensity of the hydrogen bonds). This is why water form drops.

But also, there is a strong cohesive force between the polar water molecules and the polar glass molecules in the cylinder.

The concave meniscus is the result of the fact that the adhesive force between the surface of the glass cylinder and the molecules of water overcomes the cohesive force of the water molecules.