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Description
The activity (relative activity) of a dissolved substance X equals the concentration, cX [mol/L] at high dilution (this applies frequently to dilutions <10 mmol/L) divided by the unit concentration, c° = 1 mol/L:
aX = cX/c°
For dissolved gases, the activity is the partial pressure, pX [Pa], devided by the unit partial pressure, p° = 1 Pa. The partial pressure is related to the concentration of the gas by the solubility, SX [Pa/mol]:
aX = cX*SX/p°
In general, the relative activity is defined by the chemical potential, µX '"`UNIQ--ref-00000001-QINU`"'
aX = exp[(µX-µ°)/RT]
The activity is a dimensionless quantity.
Abbreviation: a
Reference: Cohen 2008 IUPAC Green Book
MitoPedia concepts:
Ergodynamics
MitoPedia topics:
Substrate and metabolite
Activity in other contexts
- Activity of a radioactive substance, A = — dNB/dt [Bq] [2]
- Catalytic activity
- Free ROUTINE activity, ROUTINE activity
References
- ↑ Cohen ER, Cvitas T, Frey JG, Holmström B, Kuchitsu K, Marquardt R, Mills I, Pavese F, Quack M, Stohner J, Strauss HL, Takami M, Thor HL (2008) Quantities, Units and Symbols in Physical Chemistry, IUPAC Green Book, 3rd Edition, 2nd Printing, IUPAC & RSC Publishing, Cambridge. - »Bioblast link«
- ↑ Cohen ER, Cvitas T, Frey JG, Holmström B, Kuchitsu K, Marquardt R, Mills I, Pavese F, Quack M, Stohner J, Strauss HL, Takami M, Thor HL (2008) Quantities, Units and Symbols in Physical Chemistry, IUPAC Green Book, 3rd Edition, 2nd Printing, IUPAC & RSC Publishing, Cambridge. - »Bioblast link«