Description
The activity (relative activity) is a dimensionless quantity related to the concentration or partial pressure of dissolved substances. The activity of a dissolved substance B equals the concentration, cB [mol/L] at high dilution (this applies frequently to dilutions <10 mmol/L) divided by the unit concentration, c° = 1 mol/L:
aB = cB/c°
For a dissolved gas G, the activity is the partial pressure, pG [Pa], divided by the unit partial pressure, p° = 1 Pa. The partial pressure is related to the concentration of the gas by the solubility, SG [Pa/mol] (see Oxygen solubility):
aG = cG·SG/p°
In general, the relative activity is defined by the chemical potential, µX
aX = exp[(µX-µ°)/RT]
Abbreviation: a
Reference: Cohen 2008 IUPAC Green Book
Activity in other contexts
- Activity of a radioactive substance, A = — dNB/dt [Bq] [1]
- Bq is the becquerel [s-1]
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«
MitoPedia concepts:
Ergodynamics
MitoPedia topics:
Substrate and metabolite