How to measure atmospheric pressure?

Does the air have weight? If you still don't know, know now: there is a specific device to measure the pressure that the air exerts on us. It consists of a 100 cm long capillary tube, closed at one end and containing mercury. This tube is immersed in a container that contains mercury and is called the Torricelli Barometer.

If this device did not exist, it would be necessary to make numerous calculations until reaching an unreliable result. The Barometer is safe and efficient and works as follows: the mercury-filled tube shows the pressure, the liquid metal flows to the point 76 cm, this will be the pressure value obtained at sea level and is considered normal, it can be represented by 760 mmHg or 1 atmosphere (1 atm).

And who was the inventor of this handy device? the Italian scientist called Evangelista Torricelli (1608-1647) proposed in 1643 that atmospheric pressure could be measured through instruments, after Many studies then emerge the Torricelli Barometer, which received this nomenclature in honor of its inventor.

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So let's consider the following: atmospheric pressure affects the weight of the mercury column in the tube, since the higher the air pressure, the longer the mercury column. As the height of the column of mercury varies according to the altitude at which it is measured, it happens that at high altitudes the atmospheric pressure decreases and at lower altitudes it rises.

Atmospheric pressure can be calculated by multiplying the weight of the column of mercury by the density of mercury and the acceleration due to gravity.

By Líria Alves
Graduated in Chemistry

Would you like to reference this text in a school or academic work? Look:

SOUZA, Líria Alves de. "How to measure atmospheric pressure?"; Brazil School. Available in: https://brasilescola.uol.com.br/quimica/como-medir-pressao-atmosferica.htm. Accessed on June 27, 2021.