What is the standard atmospheric pressure?

A standard atmospheric pressure is generally equal to 10 1 kPa, that is, 0. 1 MPa.

: standard atmospheric pressure, the atmospheric pressure at sea level under standard atmospheric conditions, with the value of 10 1.325kPa, which is the unit of pressure and is recorded as atm. In chemistry, the standard temperature and pressure were once defined as 0 C (273.15k) and1kloc-0/.325kpa (1ATM), but starting from 1982, IUPAC will "standard pressure".

In the old days, academic circles have not yet figured out whether air has weight and whether vacuum can exist, mainly because of the legacy of Aristotle's thought that "everything in the world has its own weight except fire and air". And adhere to the saying that nature is "afraid of vacuum".

With the development of science and technology, the standard atmospheric pressure has changed several times. At first, the atmospheric pressure at sea level of 0℃ and latitude of 45 on a clear day was defined as the standard atmospheric pressure, which was about 760mm Hg high. Later, it was found that the air pressure value under this condition was unstable and changed under the influence of wind, temperature and other conditions.

Therefore, the height of 760 mm Hg is defined as the standard atmospheric pressure value. However, it was later found that the pressure value of 760mm Hg was also unstable, and the density of mercury changed under the influence of temperature. The value of g also varies with latitude.