<P> It was originally defined as the pressure exerted by 760 mm of mercury at 0 ° C and standard gravity (g = 7000980665000000000 ♠ 9.806 65 m / s). It was used as a reference condition for physical and chemical properties, and was implicit in the definition of the Centigrade (later Celsius) scale of temperature by defining 100 ° C as being the boiling point of water at this pressure . In 1954, the 10th Conférence Générale des Poids et Mesures (CGPM) adopted standard atmosphere for general use and affirmed its definition of being precisely equal to 7006101325000000000 ♠ 1013250 dynes per square centimetre (7005101325000000000 ♠ 101 325 Pa). This defined both temperature and pressure independent of the properties of particular substance . In addition (the CGPM noted) there had been some misapprehension that it "led some physicists to believe that this definition of the standard atmosphere was valid only for accurate work in thermometry ." </P> <P> In chemistry and in various industries, the reference pressure referred to in "Standard Temperature and Pressure" (STP) was commonly 1 atm (101.325 kPa) but standards have since diverged; in 1982, the International Union of Pure and Applied Chemistry (IUPAC) recommended that for the purposes of specifying the physical properties of substances, "standard pressure" should be precisely 100 kPa (1 bar). </P> <Table> Pressure units <Tr> <Th> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Th> <Th> Pascal </Th> <Th> Bar </Th> <Th> Technical atmosphere </Th> <Th> Standard atmosphere </Th> <Th> Torr </Th> <Th> Pounds per square inch </Th> </Tr> <Tr> <Th> (Pa) </Th> <Th> (bar) </Th> <Th> (at) </Th> <Th> (atm) </Th> <Th> (Torr) </Th> <Th> (lbf / in) </Th> </Tr> <Tr> <Th> 1 Pa </Th> <Td> ≡ 1 N / m </Td> <Td> 10 </Td> <Td> 6995101970000000000 ♠ 1.0197 × 10 </Td> <Td> 6994986919999999999 ♠ 9.8692 × 10 </Td> <Td> 6997750060000000000 ♠ 7.5006 × 10 </Td> <Td> 0.000 145 037 737 730 </Td> </Tr> <Tr> <Th> 1 bar </Th> <Td> 10 </Td> <Td> ≡ 100 kPa <P> ≡ 10 dyn / cm </P> </Td> <Td> 7000101970000000000 ♠ 1.0197 </Td> <Td> 6999986920000000000 ♠ 0.986 92 </Td> <Td> 7002750060000000000 ♠ 750.06 </Td> <Td> 14.503 773 773 022 </Td> </Tr> <Tr> <Th> 1 at </Th> <Td> 7004980665000000000 ♠ 98 066. 5 </Td> <Td> 6999980665000000000 ♠ 0.980 665 </Td> <Td> ≡ 1 kgf / cm </Td> <Td> 0.967 841 105 354 1 </Td> <Td> 735.559 240 1 </Td> <Td> 14.223 343 307 120 3 </Td> </Tr> <Tr> <Th> 1 atm </Th> <Td> 7005101325000000000 ♠ 101 325 </Td> <Td> 7000101325000000000 ♠ 1.013 25 </Td> <Td> 7000103319999999999 ♠ 1.0332 </Td> <Td> </Td> <Td> 760 </Td> <Td> 14.695 948 775 514 2 </Td> </Tr> <Tr> <Th> 1 Torr </Th> <Td> 133.322 368 421 </Td> <Td> 0.001 333 224 </Td> <Td> 0.001 359 51 </Td> <Td> 1 / 760 ≈ 0.001 315 789 </Td> <Td> 1 Torr <P> ≈ 1 mmHg </P> </Td> <Td> 0.019 336 775 </Td> </Tr> <Tr> <Th> 1 lbf / in </Th> <Td> 6894.757 293 168 </Td> <Td> 0.068 947 573 </Td> <Td> 0.070 306 958 </Td> <Td> 0.068 045 964 </Td> <Td> 51.714 932 572 </Td> <Td> ≡ 1 lbf / in </Td> </Tr> </Table> <Tr> <Th> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Th> <Th> Pascal </Th> <Th> Bar </Th> <Th> Technical atmosphere </Th> <Th> Standard atmosphere </Th> <Th> Torr </Th> <Th> Pounds per square inch </Th> </Tr>

1 bar is equal to how many atmospheric pressure