What does alcohol and mercury contain that makes a thermometer work?
Answer:
In a mercury or alcohol thermometer the liquid expands as it is heated and contracts when it is cooled, so the length of the liquid column is longer or shorter depending on the temperature.
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
Early thermometers used water, but because water freezes there was no way to measure temperatures less than the freezing point of water. So, alcohol, which freezes at temperature below the point where water freezes, was used...
Both alcohol and mercury expand when heated, and so a thin stream of either will move up a narrow tube. The bulk of the liquid is stored in a bulb at the bottom of the thermometer, which is connected to the narrow tube. This is how thermometers work.
Mercury is a glittering liquid metal. Finding the reading is easy.It will not stick in to the wall of capillary tube.The alcohol will easily expands for the heat.To find the level normally we add red color in it.
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