a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -
1. measurement of atmospheric pressure
2. determining the altitude of a place
3. weather forecasting
4. calibration and checking of aneroid barometers
5. application in fluid mechanics
6. measurement of pressure in aircrafts
7. surface weather analysis
8. preparation of barographs
9. usage in physical sciences like physics, astronomy & chemistry
10. preparation of aircraft altimeters
characteristics of mercury barometer : -
1.used to define and measure atmospheric pressure.
2.on the average at sea level the column of mercury rises to a height of about 760 mm.
3.this quantity is equal to 1 atmosphere.
4.it is also known as standard atmospheric pressure.
5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.
the ideal gas law equation is as follows
pv = nrt
where p - pressure
v - volume
n - number of moles
r - universal gas constant
t - temperature
so if the pressure, volume and temperature are already known
we are left with n and r
since r is the universal gas constant that has a known fixed value then r too is known
so we are left with 'n'
once we know temperature volume and pressure
we can find the number of moles of gas present using the ideal gas law equation
this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.