Difference between revisions of "Activity"

Revision as of 07:38, 18 October 2018

high-resolution terminology - matching measurements at high-resolution

Activity

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, c_B [mol/L] at high dilution (this applies frequently to dilutions <10 mmol/L) divided by the unit concentration, c° = 1 mol/L:

a_B = c_B/c°

For a dissolved gas G, the activity is the partial pressure, p_G [Pa], divided by the unit partial pressure, p° = 1 Pa. The partial pressure is related to the concentration of the gas by the solubility, S_G [Pa/mol] (see Oxygen solubility):

a_G = c_G·S_G/p°

In general, the relative activity is defined by the chemical potential, µ_X

a_X = exp[(µ_X-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

[1] 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«

[1]

@@ Line 1: / Line 1: @@
 {{MitoPedia
 |abbr=''a''
-|description=The '''activity''' (relative activity) of a dissolved substance X equals the [[concentration]], ''c''X [mol/L] at high dilution (this applies frequently to dilutions <10 mmol/L) divided by the unit concentration, ''c''° = 1 mol/L:
+|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]], ''c''<sub>B</sub> [mol/L] at high dilution (this applies frequently to dilutions <10 mmol/L) divided by the unit concentration, ''c''° = 1 mol/L:
-  ''a''X = ''c''X/''c''°
+  ''a''<sub>B</sub> = ''c''<sub>B</sub>/''c''°
-For dissolved gases, the activity is the partial pressure, ''p''X [Pa], devided by the unit partial pressure, ''p''° = 1 Pa. The partial pressure is related to the concentration of the gas by the [[solubility]], ''S''X [Pa/mol]:
+For a dissolved gas G, the activity is the partial pressure, ''p''<sub>G</sub> [Pa], divided by the unit partial pressure, ''p''° = 1 Pa. The partial pressure is related to the concentration of the gas by the [[solubility]], ''S''<sub>G</sub> [Pa/mol] (''see'' [[Oxygen solubility]]):
-  ''a''X = ''c''X*''S''X/''p''°
+  ''a''<sub>G</sub> = ''c''<sub>G</sub>·''S''<sub>G</sub>/''p''°
-In general, the relative activity is defined by the chemical potential, ''µ''X <ref>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. - [[Cohen 2008 IUPAC Green Book |»Bioblast link«]]</ref>
+In general, the relative activity is defined by the chemical potential, ''µ''<sub>X</sub>
-  ''a''X = exp[(''µ''X-''µ''°)/''RT'']
+  ''a''<sub>X</sub> = exp[(''µ''<sub>X</sub>-''µ''°)/''RT'']
-The activity is a dimensionless quantity.
 |info=[[Cohen 2008 IUPAC Green Book]]
-}}
-{{MitoPedia concepts
-|mitopedia concept=Ergodynamics
-}}
-{{MitoPedia methods}}
-{{MitoPedia O2k and high-resolution respirometry}}
-{{MitoPedia topics
-|mitopedia topic=Substrate and metabolite
 }}
 == Activity in other contexts ==
 ::::* Activity of a radioactive substance, ''A'' = — d''N''B/d''t'' [Bq] <ref>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. - [[Cohen 2008 IUPAC Green Book |»Bioblast link«]]</ref>
+:::::: Bq is the becquerel [s<sup>-1</sup>]
 ::::* [[Catalytic activity]]
 ::::* [[Free ROUTINE activity]], [[ROUTINE respiration |ROUTINE activity]]
@@ Line 26: / Line 18: @@
 == References ==
 <references/>
+{{MitoPedia concepts
+|mitopedia concept=Ergodynamics
+}}
+{{MitoPedia topics
+|mitopedia topic=Substrate and metabolite
+}}