Question

Why mercury is preferred over alcohol in clinical thermometer?

Answer 1

because mercury is a volatile substance and has higher boiling point therefore dont vaporize fast

Answer 2

As compared to Alcohol, Mercury is more visible being opaque and shiny. It doesn't stick to the walls of the thermometer. Due to its larger cohesive forces, it remains altogether within the capillary tube (but alcohol may get separated inside the tube being less dense and weaker cohesive forces). As a metal, Mercury can expand by getting in contact even with very less amount of heat, therefore is more sensitive. Has a boiling point of 357 degrees and enables us to measure the temperature that high.