What are the properties of a good thermometric liquid?

Answer 1

a liquid filled thermometer reacts to the temperature it is subject to; by the liquid increasing in pressure and expanding , which results in movement of the liquid /"medium" that is used to fill it ; in most cases ;; Mercury substance .

...

note , whilst the most common type of device used is the Mercury in glass thermometer which is used in science laboratories .

..

but be aware that there are other types used; but in industrial applications.

..

1 type used in a engineering role ; is mercury in steel type of thermometer detector .

this is a measuring device which has a steel sensor device ; maybe about 2 inches 50 . mm . length , and this is joined to a steel capillary tube which has some degree of flexibility , and will have a long length until it is connected to the measuring scale .

the capillary tube has a hollow interior , which allows the mercury fluid to move within when subject to heat / and expand .

the increase in pressure is effected to another device called the measuring pressure tube .

the tube is commonly known as a bourdon tube pressure gauge .

and once again the capillary tube will be connected physically to the gauge tube .

the increase in mercury pressure , will cause the fluid substance to expand and move upwards in the capillary tube to the bourdon tube in the gauge .

this action causes the bourdon tube to move by deflection , in an arc because the tube is tensile, and causes itself to move outward and this small movement , is transmitted by a small brass gear mechanism linkage to a central pointer system , which when moved and effected appears to move across a scale which consequently indicates a value on a scale .

and the operator can read off a value from the measuring scale .

..........

so the properties of a liquid filled thermometer are ;

it should have a safe method of being sealed fully across its structure body between the measuring sensing device to the measuring scale .

..

this is because the accuracy of measuring system depends on the sealing .

and because the interior will contain a substance which is harmful to health .,

and the repeatability of measuring accuracy depends on safe

e sealing of pressure whithin the system,

Answer 2

For most thermometers, the liquid needs to be able to stand up to 100 degrees Celsius, and 0 degrees Celsius, or else the liquid will freeze or boil and it will not work properly. It also has to be colored, so you can read the etchings or markings properly, and you can read the temperature. The liquid also needs to be relatively cheap, so the factories can provide it and make a profit. And today, colored alcohol is most commonly used, because mercury was very toxic and was poisoning humans, and the fish who were in the lakes they would dump the mercury into. So usually the liquid needs to be non-toxic.

Answer 3

If it's silvery, it's probably mercury though if it's a newer thermometer it may be some low melting alloy such as Galinstan. If it's red or blue, it's most likely alcohol with a small amount of coloring added to make it easier to see.

Answer 4

mercury is affected by temperature very easily a small amount is put into a test tube it doesnt take much for the liquid to expand or contract so that we can see the change in temperature.

Marcury has a melting point of −38.83 °C and boiling point of 356.73 °C.

Answer 5

- heating and cooling must be rapid

- heating and cooling must be reversible

- specified monotonic relation between the volume and temperature

Answer 6

It should not freeze or boil when it is being used

Answer 7

liquid must expand or contract uniformly with a change in temperature.

Answer 8

This property is the proportional dilatation of liquids depending on temperature.