TNT equivalentRediger

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Diagram of explosive yield vs mushroom cloud height, illustrating the difference between 22 kiloton Fat Man and 15 megaton Castle Bravo explosions

TNT equivalent is a method of quantifying the energy released in explosions. The ton (or tonne) of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT. The megaton is a unit of energy equal to 4.184 petajoules[1].

The kiloton and megaton of TNT have traditionally been used to rate the energy output, and hence destructive power, of nuclear weapons (see nuclear weapon yield). This unit is written into various nuclear weapon control treaties, and gives a sense of destructiveness as compared with ordinary explosives, like TNT. More recently, it has been used to describe the energy released in other highly destructive events, such as asteroid impacts. However, TNT is not the most energetic of conventional explosives. Dynamite, for example, has more than 60% more energy density (approximately 7.5 MJ/kg, compared to 4.6 MJ/kg for TNT).


A gram of TNT releases 980–1100 calories upon explosion. To define the tonne of TNT, this was arbitrarily standardized by letting 1000 thermochemical calories = 1 gram TNT = 4184 J (exactly).[2]

This definition is a conventional one. Explosives' energy is normally calculated using the thermodynamic work energy of detonation, which for TNT has been accurately measured at 1120 calth/g from large numbers of air blast experiments and theoretically calculated to be 1160 calth/g.[3]

The measured pure heat output of a gram of TNT is only 651 thermochemical calories ≈ 2724 J,[4] but this is not the important value for explosive blast effect calculations.

A kiloton of TNT can be visualized as a cube of TNT a bit under 10 meters on a side.

Grams TNT Symbol Tons TNT Symbol Energy
gram of TNT g microton of TNT μt 4.184×103 J
kilogram of TNT kg milliton of TNT mt 4.184×106 J
megagram of TNT Mg ton of TNT t 4.184×109 J
gigagram of TNT Gg kiloton of TNT kt 4.184×1012 J
teragram of TNT Tg megaton of TNT Mt 4.184×1015 J
petagram of TNT Pg gigaton of TNT Gt 4.184×1018 J


  • Conventional bunker buster bombs yield range from less than 1 ton to MOAB's 11 tonnes.
  • Minor Scale, a 1985 United States conventional explosion utilizing 4.800 short tons (4.400 t) of ANFO explosive to simulate a 4 kilotons of TNT (17 TJ) nuclear explosion, is believed to be the largest planned detonation of conventional explosives in history.
  • The Little Boy atomic bomb dropped on Hiroshima on August 6, 1945, exploded with an energy of about 15 kilotons of TNT (63 TJ). The nuclear weapons currently in the arsenal of the United States range in yield from 0,3 kt (1,3 TJ)* to 1,2 Mt (5,0 PJ)* equivalent, for the B83 strategic bomb.
  • During the Cold War, the United States developed hydrogen bombs with a maximum theoretical yield of 25 megatons of TNT (100 PJ); the Soviet Union developed a prototype weapon, nick-named the Tsar Bomba, which was tested at 50 Mt (210 PJ), but had a maximum theoretical yield of 100 Mt (420 PJ).[5] The actual destructive potential of such weapons can vary greatly depending on conditions, such as the altitude at which they are detonated, the nature of the target they are detonated against, and the physical features of the landscape where they are detonated.
  • 1 megaton of TNT (4,2 PJ), when converted to kilowatt-hours, produces enough energy to power the average American household (in the year 2007) for 103,474 Years.[6] For example, the 30 Mt (130 PJ) estimated upper limit blast power of the Tunguska event could power the aforementioned home for just over 3,104,226 years. To put that in perspective: the blast energy could power the entire United States for 3.27 days.[7]
  • Megathrust earthquakes record huge MW values, or total energy released. The 2004 Indian Ocean Earthquake released 9.560 gigatons of TNT (40.000 EJ) equivalent, but its ME (surface rupture energy, or potential for damage) was far smaller at 26,3 megatons of TNT (110 PJ)*.
  • On a much grander scale, supernova explosions give off about 1044 joules of energy, which is about ten octillion (1028) megatons of TNT.
  • The maximum theoretical energy from total conversion of matter to energy when 1 kilogram (2,2 lb) of antimatter annihilates with 1 kilogram of matter the reaction is 17.975×1016 J, which is equal to 42.92 Mt. This is given by the equation E = mc2.[8]

See alsoRediger


  1. ^ Joules to Megatons Conversion Calculator
  2. ^ NIST Guide for the Use of the International System of Units (SI): Appendix B8—Factors for Units Listed Alphabetically
  3. ^ Cooper, Paul. Explosives Engineering, New York: Wiley-VCH, 1996, p. 406.
  4. ^ "Physics for Future Presidents, a textbook", 2001–2002, Richard A. Muller, Chapter 1. Energy, Power, and Explosions
  5. ^ See Currently deployed U.S. nuclear weapon yields, Complete List of All U.S. Nuclear Weapons, Tsar Bomba, all from Carey Sublette's Nuclear Weapon Archive.
  6. ^ "Frequently Asked Questions – Electricity". United States Department of Energy. 2009-10-06. Hentet 2009-10-21.  (Calculated from 2007 value of 936 kWh monthly usage)
  7. ^ "Country Comparison :: Electricity - consumption". The World Factbook. CIA. Hentet 2009-10-22.  (Calculated from 2007 value of 3,892,000,000,000 kWh annual usage)
  8. ^ In antiproton annihilation, about 50% of this energy is carried off by effectively invisible neutrinos (see S.K. Borowski,Comparison of Fusion/Antiproton Propulsion systems); in contrast, almost 100% of electron-positron annihilation events emit their energy entirely as gamma rays.


616 ("six hundred and sixteen", or "six sixteen" in American English) is believed by some Christians to have been the original Number of the Beast in the Book of Revelation in the Christian Bible.--Citation needed|date=December 2009-- Different early versions of the Book of Revelation gave different numbers, and 666 had been widely accepted as the original number. In 2005, however, a fragment of papyrus 115 was revealed, containing the earliest known version of that part of the Book of Revelation discussing the Number of the Beast. It gave the number as 616, suggesting that this may have been the original.[1]


A ball-and-stick model of the Lewis adduct between BH3 and THF

An adduct (from the Latin adductus, "drawn toward") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components, with formation of two chemical bonds and a net reduction in bond multiplicity in at least one of the reactants.[2] The resultant is considered a distinct molecular species. Examples include the adduct between hydrogen peroxideand sodium carbonate to give sodium percarbonate, and the addition of sodium bisulfite to an aldehyde to give a sulfonate.

Adducts often form between Lewis acids and Lewis bases. A good example would be the formation of adducts between the Lewis acid borane and the oxygen atom in the Lewis bases,tetrahydrofuran (THF, IUPAC: oxacyclopentane): BH3•O(CH2)4or diethyl ether: BH3•O(CH3CH2)2. Compounds or mixtures that cannot form an adduct because of steric hindrance are called frustrated Lewis pairs.

Adducts are not necessarily molecular in nature. A good example from solid-state chemistry are the adducts of ethylene or carbon monoxide of CuAlCl4. The latter is a solid with an extended lattice structure. Upon formation of the adduct a new extended phase is formed in which the gas molecules are incorporated (inserted) as ligands of the copper atoms within the structure. This reaction can also be considered a reaction between a base and a Lewis acid with the copper atom in the electron-receiving and the pi electrons of the gas molecule in the donating role.[3]

Adduct ionsRediger

An adduct ion is formed from a precursor ion and contains all of the constituent atoms of that ion as well as additional atoms or molecules.[4] Adduct ions are often formed in a mass spectrometer ion source.


  1. ^ The Other Number of the Beast
  2. ^ (engelsk) International Union of Pure and Applied Chemistry. "adduct". Compendium of Chemical Terminology Internet-udgave.
  3. ^ Capracotta, Michael D.; Sullivan, Roger M.; Martin, James D. (2006). "Sorptive Reconstruction of CuMCl4 (M = Al and Ga) upon Small-Molecule Binding and the Competitive Binding of CO and Ethylene". J. Am. Chem. Soc. 128 (41): 13463-13473. doi:10.1021/ja063172q. 
  4. ^ (engelsk) International Union of Pure and Applied Chemistry. "adduct ion (in mass spectrometry)". Compendium of Chemical Terminology Internet-udgave.

International Union of Pure and Applied PhysicsRediger

Fil:IUPAP Logo.png
The logo of IUPAP.

The International Union of Pure and Applied Physics (IUPAP) is an internationalnon-governmental organization devoted to the advancement of physics. It was established in 1922 and the first General Assembly was held in 1923 in Paris.

The aims of the Union are: to stimulate and promote international cooperation in physics; to sponsor suitable international meetings and to assist organizing committees; to foster the preparation and the publication of abstracts of papers and tables of physical constants; to promote international agreements on the use of symbols, units, nomenclature and standards; to foster free circulation of scientists; to encourage research and education.

The Union is governed by its General Assembly, which meets every three years. The Council is its top executive body, supervising the activities of the nineteen specialized International Commissions and the three Affiliated Commissions. The Union is composed of Members representing identified physics communities. At present 49 Members adhere to IUPAP.

IUPAP is a member of the International Council for Science (ICSU).

The SUNAMCO Commission of the IUPAP published the book entitled Symbols, Units, Nomenclature and Fundamental Constants in Physics, 1987 Revision, by E.R. Cohen and P. Giacomo which is also known as the red book, I.U.P.A.P.-25, or SUNAMCO 87-1. This book was reprinted from Physica, Vol. 146A, Nos. 1-2, p. 1 (November, 1987) [1]. The SP Technical Research Institute of Sweden website [2] makes the 1987 edition of the Symbols, Units, Nomenclature and Fundamental Constants in Physics available on the internet. [3]

See alsoRediger

International Union of Pure and Applied Chemistry

External linksRediger

Category:International scientific organizations
Category:International nongovernmental organizations
Category:Physics organizations
Category:Learned societies
Category:Standards organizations

Standard conditions for temperature and pressureRediger

In chemistry, standard conditions for temperature and pressure (informally abbreviated as STP) are standard sets of conditions for experimental measurements, to allow comparisons to be made between different sets of data. The most used standards are those of the International Union of Pure and Applied Chemistry (IUPAC) and the National Institute of Standards and Technology (NIST) but are far from being universally accepted standards. Other organizations have established a variety of alternative definitions for their standard reference conditions. The current version of IUPAC's standard is a temperature of 0 °C (273.15 K, 32 °F) and an absolute pressure of 100 kPa (14.504 psi, 0.986 atm)[1], while NIST's version is a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 101.325 kPa (14.696 psi, 1 atm).

In industry and commerce, standard conditions for temperature and pressure are often necessary to define the standard reference conditions to express the volumes of gases and liquids and related quantities such as the rate of volumetric flow (the volumes of gases and liquids vary significantly with temperature and pressure). However many technical publications (books, journals, advertisements for equipment and machinery) simply state "standard conditions" without specifying them, often leading to confusion and errors.


Past useRediger

In the last five to six decades, professionals and scientists using the metric system of units defined the standard reference conditions of temperature and pressure for expressing gas volumes as being 0 °C (273,15 K; 32,00 °F) and 101.325 kPa (1 atm or 760 Torr). During those same years, the most commonly used standard reference conditions for people using the imperial or U.S. customary systems was 60 °F (15,56 °C; 288,71 K) and 14.696 psi (1 atm) because it was almost universally used by the oil and gas industries worldwide. However, the above two definitions are no longer the most commonly used in either system of units

Current useRediger

Many different definitions of standard reference conditions are currently being used by organizations all over the world. The table below lists a few of them, but there are more. Some of these organizations used other standards in the past, such as IUPAC which currently defines standard reference conditions as being 0 °C and 100 kPa (1 bar) of pressure rather since 1982, in contrast to their old standard of 0 °C and 101.325 kPa (1 atm).[2] Another example is from the oil industry. While a standard of 60 °F and 14.696 psi was used in the past, the current usage (particularly in North America) is predominantly of 60 °F and 14.73 psi.

Natural gas companies in Europe and South America have adopted 15 °C (59 °F) and 101.325 kPa (14.696 psi) as their standard gas volume reference conditions.[3][4][5] Also, the International Organization for Standardization (ISO), the United States Environmental Protection Agency (EPA) and National Institute of Standards and Technology (NIST) each have more than one definition of standard reference conditions in their various standards and regulations.

The SATP used for presenting chemical thermodynamic properties (such as those published by the National Bureau of Standards) is standardized at 100 kPa (1 bar) but the temperature may vary and usually needs to be specified separately if complete information is desired (see standard state). Some standards are specified at certain humidity level.

Table 1: Standard reference conditions in current use
Temperature Absolute pressure Relative humidity Publishing or establishing entity
°C kPa % RH
0 100.000   IUPAC (present definition)[1]
0 101.325   IUPAC (former definition)[1], NIST[6], ISO 10780[7]
15 101.325 0[8][9] ICAO's ISA,[8] ISO 13443,[9] EEA,[10] EGIA[11]
20 101.325   EPA,[12] NIST[13]
25 101.325   EPA[14]
25 100.000   SATP[15]
20 100.000 0 CAGI[16]
15 100.000   SPE[17]
20 101.3 50 ISO 5011[18]
°F psi % RH
60 14.696   SPE,[17] U.S. OSHA,[19] SCAQMD[20]
60 14.73   EGIA,[11] OPEC,[21] U.S. EIA[22]
59 14.503 78 U.S. Army Standard Metro[23][24]
59 14.696 60 ISO 2314, ISO 3977-2[25]
°F in Hg % RH
70 29.92 0 AMCA,[26][27] air density = 0.075 lbm/ft³. This AMCA standard applies only to air.


  • EGIA: Electricity and Gas Inspection Act (of Canada)
  • SATP: Standard Ambient Pressure and Temperature

International Standard AtmosphereRediger

In aeronautics and fluid dynamics the term "International Standard Atmosphere" is often used to denote the variation of the principal thermodynamic variables (pressure, temperature, density, etc.) of the atmosphere with altitude at mid latitudes.

Standard laboratory conditionsRediger

Due to the fact that many definitions of standard temperature and pressure differ in temperature significantly from standard laboratory temperatures (e.g., 0 °C vs. ~25 °C), reference is often made to "standard laboratory conditions" (a term deliberately chosen to be different from the term "standard conditions for temperature and pressure", despite its semantic near identity when interpreted literally). However, what is a "standard" laboratory temperature and pressure is inevitably culture-bound, given that different parts of the world differ in climate, altitude and the degree of use of heat/cooling in the workplace. For example, schools in New South Wales, Australia use 25 °C at 100 kPa for standard laboratory conditions.[28]

ASTM International has published Standard ASTM E41- Terminology Relating to Conditioning and hundreds of special conditions for particular materials and test methods. Other standards organizations also have specialized standard test conditions.

Molar volume of a gasRediger

It is equally as important to indicate the applicable reference conditions of temperature and pressure when stating the molar volume of a gas[29] as it is when expressing a gas volume or volumetric flow rate. Stating the molar volume of a gas without indicating the reference conditions of temperature and pressure has no meaning and it can cause confusion.

The molar gas volumes can be calculated with an accuracy that is usually sufficient by using the universal gas law for ideal gases. The usual expression is:


…which can be rearranged thus:


where (in SI metric units):

P = the absolute pressure of the gas, in Pa
n = amount of substance, in mol
V = the volume of the gas, in m3
T = the absolute temperature of the gas, in K
R = the universal gas law constant of 8.3145 m3·Pa/(mol·K)

or where (in customary USA units):

P = the absolute pressure of the gas, in psi
n = number of moles, in lbmol
V = the volume of the gas, in ft3/lbmol
T = the absolute temperature of the gas absolute, in °R
R = the universal gas law constant of 10.7316 ft3·psi/(lbmol·°R)

The molar volume of any ideal gas may be calculated at various standard reference conditions as shown below:

  • V/n = 8.3145 × 273.15 / 101.325 = 22.414 m3/kmol at 0 °C and 101.325 kPa
  • V/n = 8.3145 × 273.15 / 100.000 = 22.711 m3/kmol at 0 °C and 100 kPa
  • V/n = 8.3145 × 298.15 / 101.325 = 24.466 m3/kmol at 25 °C and 101.325 kPa
  • V/n = 8.3145 × 298.15 / 100.000 = 24.790 m3/kmol at 25 °C and 100 kPa
  • V/n = 10.7316 × 519.67 / 14.696 = 379.48 ft3/lbmol at 60 °F and 14.696 psi
  • V/n = 10.7316 × 519.67 / 14.730 = 378.61 ft3/lbmol at 60 °F and 14.73 psi

The technical literature can be confusing because many authors fail to explain whether they are using the universal gas law constant R, which applies to any ideal gas, or whether they are using the gas law constant Rs, which only applies to a specific individual gas. The relationship between the two constants is Rs = R / M, where M is the molecular weight of the gas.

The US Standard Atmosphere uses 8.31432 m3·Pa/(mol·K) as the value of R for all calculations. (See Gas constant)


  1. ^ a b c A. D. McNaught, A. Wilkinson (1997). Compendium of Chemical Terminology, The Gold Book (PDF) (2nd udgave). Blackwell Science. ISBN 0865426848. Standard conditions for gases: Temperature, 273.15 K [...] and pressure of 105 pascals. IUPAC recommends that the former use of the pressure of 1 atm as standard pressure (equivalent to 1.01325 × 105 Pa) should be discontinued. 
  2. ^ A. D. McNaught, A. Wilkinson (1997). Compendium of Chemical Terminology, The Gold Book (PDF) (2nd udgave). Blackwell Science. ISBN 0865426848. Standard pressure: Chosen value of pressure denoted by po or p°. In 1982 IUPAC recommended the value 105 Pa, but prior to 1982 the value 101 325 Pa (= 1 atm) was usually used. 
  3. ^ Gassco. "Concepts – Standard cubic meter (scm)". Hentet 2008-07-25. Scm: The usual abbreviation for standard cubic metre – a cubic metre of gas under a standard condition, defined as an atmospheric pressure of 1.01325 bar and a temperature of 15°C. This unit provides a measure for gas volume. 
  4. ^ Nord Stream (2007). "Status of the Nord Stream pipeline route in the Baltic Sea" (PDF). Hentet 2008-07-25. bcm: Billion Cubic Meter (standard cubic metre – a cubic metre of gas under a standard condition, defined as an atmospheric pressure of 1 atm and a temperature of 15 °C.)  Ukendt parameter |month= ignoreret (hjælp)
  5. ^ Metrogas (2004). "Natural gas purchase and sale agreement". Hentet 2008-07-25. Natural gas at standard condition shall mean the quantity of natural gas, which at a temperature of fifteen (15) Celsius degrees and a pressure of 101.325 kilopascals occupies the volume of one (1) cubic meter.  Ukendt parameter |month= ignoreret (hjælp)
  6. ^ NIST (1989). "NIST Standard Reference Database 7 – NIST Electron and Positron Stopping Powers of Materials Database". Hentet 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).  Tjek datoværdier i |access-date= (hjælp)
  7. ^ ISO (1994), ISO 10780:1994 : Stationary source emissions - Measurement of velocity and volume flowrate of gas streams in ducts. 
  8. ^ a b Robert C. Weast (Editor) (1975). Handbook of Physics and Chemistry (56th udgave). CRC Press. s. F201-F206. ISBN 0-87819-455-X. 
  9. ^ a b "Natural gas – Standard reference conditions", ISO 13443, International Organization for Standardization, Geneva, Switzerland  ISO Standards Catalogue
  10. ^ "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
  11. ^ a b "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
  12. ^ "Standards of Performance for New Sources", 40 CFR--Protection of the Environment, Chapter I, Part 60, Section 60.2, 1990  New Source Performance Standards
  13. ^ "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
  14. ^ "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
  15. ^ "Table of Chemical Thermodynamic Properties", National Bureau of Standards (NBS), Journal of Physics and Chemical Reference Data, 1982, Vol. 11, Supplement 2.
  16. ^ "Glossary", 2002, Compressed Air and Gas Institute, Cleveland, OH, USA  Glossary
  17. ^ a b The SI Metric System of Units and SPE Metric Standard (Notes for Table 2.3, on PDF page 25 of 42 PDF pages, define two different sets of reference conditions, one for the standard cubic foot and one for the standard cubic meter)
  18. ^ "Air Intake Filters", ISO 5011:2002, International Organization for Standardization, Geneva, Switzerland ISO
  19. ^ "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
  20. ^ "Rule 102, Definition of Terms (Standard Conditions)", Amended December 2004, South Coast Air Quality Management District, Los Angeles, California, USA  SCAQMD Rule 102
  21. ^ "Annual Statistical Bulletin", 2004, Editor-in-chief: Dr. Omar Ibrahim, Organization of the Petroleum Exporting Countries, Vienna, Austria  OPEC Statistical Bulletin
  22. ^ "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
  23. ^ Sierra Bullets L.P. "Chapter 3 – Effects of Altitude and Atmospheric Conditions". Rifle and Handgun Reloading Manual, 5th Edition. "Effects of Altitude and Atmospheric Conditions", Exterior Ballistics Section, Sierra's "Rifle and Handgun Reloading Manual, 5th Edition", Sedalia, MO, USA  Exterior Ballistics
  24. ^ 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.
  25. ^ "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
  26. ^ ANSI/AMCA Standard 210, "Laboratory Methods Of Testing Fans for Aerodynamic Performance Rating", as implied here: when accessed on October 17, 2007
  27. ^ 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)
  28. ^ Peter Gribbon (2001). Excel HSC Chemistry Pocket Book Years 11-12. Pascal Press. ISBN 1-74020-303-8. 
  29. ^ Fundamental Physical Properties: Molar Volumes (CODATA values for ideal gases as listed on a NIST website page)

See alsoRediger

External linksRediger