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The therm (symbol, thm) is a non-SI unit of heat energy equal to 100,000 British thermal units (BTU), [1] and approximately 105 megajoules, 29.3 kilowatt-hours, 25,200 kilocalories and 25.2 thermies. One therm is the energy content of approximately 100 cubic feet (2.83 cubic metres) of natural gas at standard temperature and pressure .
The Green Book is a direct successor of the Manual of Symbols and Terminology for Physicochemical Quantities and Units, originally prepared for publication on behalf of IUPAC's Physical Chemistry Division by M. L. McGlashen in 1969. A full history of the Green Book's various editions is provided in the historical introduction to the third edition.
Contrast chemical synthesis. chemical element See element. chemical formula Any of various means of concisely displaying information about the chemical composition of a compound or molecule using letters, numbers, and/or typographical symbols. Chemical formulas, such as empirical and molecular formulas, can only indicate the identities and ...
The first and second law of thermodynamics are the most fundamental equations of thermodynamics. They may be combined into what is known as fundamental thermodynamic relation which describes all of the changes of thermodynamic state functions of a system of uniform temperature and pressure.
A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs.
The initial application of thermodynamics to mechanical heat engines was quickly extended to the study of chemical compounds and chemical reactions. Chemical thermodynamics studies the nature of the role of entropy in the process of chemical reactions and has provided the bulk of expansion and knowledge of the field. Other formulations of ...
Chemical formula Synonyms CAS number CAgO carbonylsilver: CCl 2 F 2: dichlorodifluoromethane freon-12: 75-71-8 CCl 4: carbon tetrachloride tetrachloromethane: 56-23-5 C(CN) 4: tetracyanomethane: 24331-09-7 CFCl 3: trichlorofluoromethane freon-11: 75-69-4 CFCl 2 CF 2 Cl: chlorotrifluoromethane freon-13: 75-72-9 CHCl 3: chloroform ...
Thermodynamic temperature is a quantity defined in thermodynamics as distinct from kinetic theory or statistical mechanics.. Historically, thermodynamic temperature was defined by Lord Kelvin in terms of a macroscopic relation between thermodynamic work and heat transfer as defined in thermodynamics, but the kelvin was redefined by international agreement in 2019 in terms of phenomena that are ...