Question

disadvantages of using water as a barometric liquid

Answer 1

Water is not a suitable barometric fluid as it has low density (~1000kg/m3) which would require a barometer around 11 meters in length, which is quite impractical. Also, it is transparent and quite dull in appearance which would make observing reading quite difficult coupled with the fact that is it has quite high specific heat which would also make it less responsive to temperature changes.

So, we normally use mercury as a barometric fluid.

Answer 2

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

1. 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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