Question

Why we don't use water as a barometric liquid

Answer 1

If water would be used in barometer,barometer tube should have the huge height of 10.3m! Mercury is 13.6 times more dense thanwater and a column weight of only 760mmHg equals the forces generated by atmospheric pressure, so the tube can be much shorter.

Answer 2

Disadvantages of using water as a barometric liquid is as follows :-

1. Disadvantages of using water as a barometric liquid is as follows :-The density of water is low (= 10³ kg/m³), so nearly 10.4 m height of water column is needed to balance the normal atmospheric pressure. but it is highly inconvenient to take a tube of height 10.4 m for a barometer.
2. The vapour pressure of water is high, so it's vapours in the vacuum space will make the reading inaccurate.
3. Water sticks with the glass tube and wets it, so the reading becomes inaccurate.
4. Water is transparent, so its surface is not easily seen while taking the observation.

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