Chemistry » Gases » Gas Pressure

Summarizing Gas Pressure

Key Concepts and Summary

Gases exert pressure, which is force per unit area. The pressure of a gas may be expressed in the SI unit of pascal or kilopascal, as well as in many other units including torr, atmosphere, and bar. Atmospheric pressure is measured using a barometer; other gas pressures can be measured using one of several types of manometers.

Key Equations

  • \(P=\phantom{\rule{0.2em}{0ex}}\frac{F}{A}\)
  • p = hρg


atmosphere (atm)

unit of pressure; 1 atm = 101,325 Pa


(bar or b) unit of pressure; 1 bar = 100,000 Pa


device used to measure atmospheric pressure

hydrostatic pressure

pressure exerted by a fluid due to gravity


device used to measure the pressure of a gas trapped in a container

pascal (Pa)

SI unit of pressure; 1 Pa = 1 N/m2

pounds per square inch (psi)

unit of pressure common in the US


force exerted per unit area


unit of pressure; \(\text{1 torr}=\phantom{\rule{0.2em}{0ex}}\frac{1}{760}\phantom{\rule{0.2em}{0ex}}\text{atm}\)

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