Ask A Scientist Chemistry Archive

Question:  Why is Mercury used in thermometers?
kennel

Answer:  Question hasn't been forgotten...it has to do with mercury's vapor
pressure, but I'm looking for something more specific.  Hang on.
-Joe Schultz

Sorry...not vapor pressure.  Mercury has a wide liquid state temperature
range (mp=-39 C and bp=357 C) so it is convenient to use in thermometers.
This range is adequate for lab measurements.  Temps out of these ranges
usually are measured with something called a thermocouple.  This converts
heat energy to electrical energy and then into a temperature.
-Joe Schultz