standard conditions for gases

https://doi.org/10.1351/goldbook.S05910
Temperature, \(273.15\ \text{K}\) (\(0\ ^{\,\unicode{x26ac}}\text{C}\)) and pressure of \(10^{5}\) pascals. IUPAC recommends that the former use of the pressure of 1 atm as @S05921@ (equivalent to \(1.01325\times 10^{5}\ \text{Pa}\)) should be discontinued.
See:
STP
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2216 [Terms] [Paper]