Answer :
Final answer:
Capillary action refers to the movement of water and mercury in narrow tubes due to intermolecular forces. Water, a polar substance, exhibits a concave meniscus and is drawn up higher in capillary tubes, whereas mercury forms a convex meniscus and does not rise as high. The height to which each liquid rises can be calculated using Jurin's law and depends on the tube's radius, liquid's surface tension, contact angle, density, and gravity.
Explanation:
The student is asking about capillary action, which is the tendency of a liquid to flow in narrow spaces without the assistance of external forces like gravity. Specifically, the student wants to know the behavior of water and mercury in capillary tubes of different radii. In the case of water, it adheres to the polar surface of glass and is drawn up into the tube exhibiting a concave meniscus. This is due to the strong adhesive forces between the water molecules and the glass. Contrarily, mercury does not adhere well to glass and forms a convex meniscus, resulting in the surface of the mercury being lower inside the tube than outside. The height to which each liquid rises is inversely related to the radius of the tube: the smaller the radius, the higher the liquid rises.
To calculate the ratio of the heights to which water and mercury are raised by capillary action in the same glass tube, you would need to know the surface tension of each liquid, the density of the liquids, the contact angle between the liquids and the glass, and the radius of the capillary tube. The height to which a liquid can rise in a tube is given by Jurin's law:
h = (2 * surface tension * cos(contact angle)) / (density * gravity * tube radius)
For water in a glass tube, the adhesive forces are strong and the contact angle is small, often approaching zero.
