标准状况

标准状况英語:标准温度与标准压力),简称「标况」。由於地表各處的溫度壓力皆不同,即使是同一地點的溫度壓强也隨測量時間不同而相異,因此為研究方便,制定出描述物質特徵的標準狀況。

-{H|zh-cn:压强; zh-hk:壓強; zh-tw:壓力 }-

在化学领域,国际纯化学和应用化学联合会(IUPAC)在1982年改变了标准温度和标准压力(STP)的定义:

  • 在1982年以前,标准状况定义为0 (273.15 K)、101325 / 105 Pa(1 atm)。1摩尔的理想氣體在STP下占有的體積為22.414升(L)。
  • 自1982年以来,标准状况定义为0 ℃(273.15 K)、100kPa,這樣的定義接近海平面冰點。1摩尔的理想氣體在STP下占有的體積為22.710953(21)L(CODATA 2010),為標準摩尔體積()。這是区别一般条件而制定的标准。

历史上由巴黎制定的通行欧洲的舊制標準如下:

  • 压强p = 1 atm = 101325 帕斯卡 = 1013.25 hPa = 101.325 kPa = 1.01325 bar.
  • 温度T = 298.15 K ≙ 25 °C,空气密度ρ = 1.184 kg/m³.
现在也使用T = 293.15 K ≙ 20 °C 空气密度ρ = 1.204 kg/m³.

化学生物化学中另外还包括定义的观察反应物浓度,一般情况下为1mol/L(1 M)。在生物化学中只有氢离子例外(H+)。限定pH为7,即10-7 mol/l H+离子浓度用于准生理条件描述,肌体条件,细胞内部条件等。

当前使用的标准状况

世界各地的组织目前正在使用许多不同的标准状况定义。 下表列出了其中的一些。 其中一些组织过去使用过其他标准。 例如,自1982年以来,IUPAC将标准参考条件定义为0°C和100 kPa(1 bar),而其旧标准为0°C和101.325 kPa(1 atm)。

标准状况參考條件
溫度絕對壓力相对湿度 出版或創立者
°CkPa% RH
0100.000 IUPAC(1982年之后正在使用的定義)
0101.325 IUPAC(1982年以前使用的定義)NIST[1], ISO 10780[2]
15101.3250[3][4]ICAO's ISA[3] ISO 13443,[4] EEA[5] EGIA[6]
20101.325 EPA[7] NIST[8]
25101.325 EPA[9]
25100.000 SATP[10]
20100.0000CAGI[11]
15100.000 SPE[12]
°Fpsi% RH
6014.696 SPE,[12] U.S. OSHA[13] SCAQMD[14]
6014.73 EGIA,[6] OPEC[15] U.S. EIA[16]
5914.50378U.S. Army Standard Metro[17][18]
5914.69660ISO 2314, ISO 3977-2[19]
°Fin Hg% RH
7029.920AMCA[20][21] air density = 0.075 lbm/ft³. This AMCA standard applies only to air.

注釋:

  • EGIA:加拿大电力和燃气检验法
  • SATP:标准的环境压力和温度
  • SCAQMD:加州南海岸空气质量管理区

气体摩尔体积

当表示气体的摩尔体积时,要指明适用的温度和压力条件。 在不指明温度和压力条件的情况下,说明气体的摩尔体积几乎没有意义并且可能引起混淆。

通过使用理想气体定律,可以计算在标准状况下的气体摩尔体积。 任何理想气体的摩尔体积可以在各种标准参考条件下计算,如下所示:

  • Vm = 8.3145 × 273.15 / 101.325 = 22.414 dm3/mol (在 0 °C 和 101.325 kPa 下)
  • Vm = 8.3145 × 273.15 / 100.000 = 22.711 dm3/mol (在 0 °C 和 100 kPa 下)
  • Vm = 8.3145 × 298.15 / 101.325 = 24.466 dm3/mol (在25 °C 和 101.325 kPa 下)
  • Vm = 8.3145 × 298.15 / 100.000 = 24.790 dm3/mol (在25 °C 和 100 kPa 下)
  • Vm = 10.7316 × 519.67 / 14.730 = 378.61 ft3/lbmol (在60 °F 和 14.73 psi 下)

参看

參考資料

  1. NIST. . 1989 [08-07-25]. If you want the program to treat the material as an ideal gas, the density will be assumed given by M/V, where M is the gram molecular weight of the gas and V is the mol volume of 22414 cm3 at standard conditions(0 deg C and 1 atm).
  2. ISO, , 1994
  3. Robert C. Weast (Editor). 56th Edition. CRC Press. 1975: F201–F206. ISBN 0-87819-455-X.
  4. "Natural gas – Standard reference conditions", ISO 13443, International Organization for Standardization, Geneva, Switzerland  ISO Standards Catalogue
  5. "Extraction, First Treatment and Loading of Liquid & Gaseous Fossil Fuels", Emission Inventory Guidebook B521, Activities 050201 - 050303, September 1999, European Environmental Agency, Copenhagen, Denmark  Emission Inventory Guidebook
  6. "Electricity and Gas Inspection Act", SOR/86-131(defines a set of standard conditions for Imperial units and a different set for metric units) Canadian Laws
  7. "Standards of Performance for New Sources", 40 CFR--Protection of the Environment, Chapter I, Part 60, Section 60.2, 1990  New Source Performance Standards
  8. "Design and Uncertainty for a PVTt Gas Flow Standard", Journal of Research of the National Institute of Standards and Technology, Vol.108, Number 1, 2003  NIST Journal 存檔,存档日期2006-04-14.
  9. "National Primary and Secondary Ambient Air Quality Standards", 40 CFR--Protection of the Environment, Chapter I, Part 50, Section 50.3, 1998  National Ambient Air Standards
  10. "Table of Chemical Thermodynamic Properties", National Bureau of Standards(NBS),Journal of Physics and Chemical Reference Data, 1982, Vol. 11, Supplement 2.
  11. "Glossary", 2002, Compressed Air and Gas Institute, Cleveland, OH, USA  Glossary 存檔,存档日期2007-10-28.
  12. The SI Metric System of Units and SPE Metric Standard 存檔,存档日期2008-12-20. 1984, Richardson, TX, USA(Notes for Table 2.3 on page 25 define standard cubic foot and standard cubic meter)
  13. "Storage and Handling of Liquefied Petroleum Gases" and "Storage and Handling of Anhydrous Ammonia", 29 CFR--Labor, Chapter XVII--Occupational Safety and Health Administration, Part 1910, Sect. 1910.110 and 1910.111, 1993  Storage/Handling of LPG 存檔,存档日期2006-07-19.
  14. "Rule 102, Definition of Terms(Standard Conditions)", Amended December 2004, South Coast Air Quality Management District, Los Angeles, California, USA  SCAQMD Rule 102 存檔,存档日期2008-12-19.
  15. "Annual Statistical Bulletin", 2004, Editor-in-chief: Dr. Omar Ibrahim, Organization of the Petroleum Exporting Countries, Vienna, Austria  OPEC Statistical Bulletin 存檔,存档日期2008-12-19.
  16. "Natural Gas Annual 2004", DOE/EIA-0131(04),December 2005, U.S. Department of Energy, Energy Information Administration, Washington, D.C., USA  Natural Gas Annual 2004
  17. Sierra Bullets L.P. . ."Effects of Altitude and Atmospheric Conditions", Exterior Ballistics Section, Sierra's "Rifle and Handgun Reloading Manual, 5th Edition", Sedalia, MO, USA  Exterior Ballistics
  18. The pressure is specified as 750 mmHg. However, the mmHg is temperature dependant, as mercury expands as temperature goes up. Here the values for the 0-20 °C range are given.
  19. "Gas turbines – Procurement – Part 2: Standard reference conditions and ratings", ISO 3977-2:1997 and "Gas turbines - Acceptance tests", ISO 2314:1989, Edition 2, International Organization for Standardization, Geneva, Switzerland ISO
  20. ANSI/AMCA Standard 210, "Laboratory Methods Of Testing Fans for Aerodynamic Performance Rating", as implied here: http://www.greenheck.com/pdf/centrifugal/Plug.pdf when accessed on October 17, 2007
  21. The standard is given as 29.92 inHg at an unspecified temperature. This most likely corresponds to a standard pressure of 101.325 kPa, converted into ~29.921 inHg at 32 °F)

外部連結

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