Description
Advancement per volume or volume-specific advancement, dtrY [molβV-1], is related to advancement, dtrY = dtrΞΎβV-1, as is the amount of substance per volume, ci (concentration [molβV-1]), related to amount, ci = = niβV-1. Advancement per volume is particularly introduced for chemical reactions, drY, and has the units of concentration. In an open system at steady-state, however, the concentration does not change as the reaction advances. Only in closed systems, specific advancement equals the change in concentration divided by the stoichiometric number,
ΞrY = Ξci/Ξ½i (closed system)
ΞrY = Ξrci/Ξ½i (general)
In general, Ξci is replaced by the partial change of concentration, Ξrci (a transformation variable or process variable), which contributes to the total change of concentration, Ξci (a system variable or variable of state). In open systems at steady-state, Ξrci is compensated by external processes, Ξextci, exerting an effect on the total concentration change, Ξci = Ξrci + Ξextci = 0.
Abbreviation: dtrY
Reference: Gnaiger (1993) Pure Appl Chem
MitoPedia concepts:
Ergodynamics
MitoPedia methods:
Respirometry
Application in respirometry
- In typical liquid phase reactions the volume of the system does not change during the reaction. When oxygen consumption (Ξ½O2 = -1 in the chemical reaction) is measured in aqueous solution, the volume-specific oxygen flux is the time derivative of the advancement of the reaction per volume [1], JV,O2 = drYO2/dt = drΞΎO2/dtβV-1 [(molβsΒ-1)βLΒ-1]. The rate of O2 concentration change is dcO2/dt [(molβLΒ-1)βsΒ-1], where concentration is cO2 = nO2βV-1. There is a difference between (1) JV,O2 [molβsΒ-1βLΒ-1] and (2) rate of concentration change [molβLΒ-1βsΒ-1]. These merge to a single expression only in a closed system. In open systems, internal transformations (catabolic flux, O2 consumption) are distinguished from external flux (such as O2 supply). External fluxes of all substances are zero in closed systems [2].