Droplets of glycerol placed on a clean glass slide remain nearly spherical
PHYSICS · Single correct · CBSE · Physics · Mechanical Properties of Fluids · Mechanical Properties of Fluids
Problem
Droplets of glycerol placed on a clean glass slide remain nearly spherical, whereas droplets of ethanol spread out to form thin films under the same conditions. Which of the following best accounts for this observation?
(a) Glycerol’s very high viscosity prevents it from flowing outward, so the droplet retains a spherical shape.
(b) Because glycerol has a much lower vapor pressure than ethanol, its droplets do not evaporate quickly and therefore do not spread.
(c) Glycerol molecules experience stronger intermolecular attractions that give the liquid a greater surface tension, so the droplet minimizes its surface area.
(d) Ethanol’s greater molar mass makes it less polar than glycerol, causing weaker cohesion and allowing the liquid to form a thin film.