Advancement per volume

high-resolution terminology - matching measurements at high-resolution

Advancement per volume

Description

Advancement per volume or volume-specific advancement, d_trY [mol∙V^-1], is related to advancement, d_trY = d_trξ∙V^-1, as is the amount of substance per volume, c_i (concentration) [mol∙V^-1], related to amount, c_i = = n_i∙V^-1. Advancement per volume is particularly introduced for chemical reactions, d_rY, where it has the dimension of a concentration. In an open system at steady-state, however, the concentration does not change as the reaction advances. Only in closed systems, specific advancement is the change in concentration divided by the stoichiometric number, Δ_rY = Δc_i/ν_i. In general, Δc_i is replaced by the partial change of concentration, Δ_rc_i, which contributes to the total change of concentration, Δc_i. In open systems at steady-state, Δ_rc_i is compensated by external processes, Δ_extc_i, exerting an effect on the total concentration change, Δc_i = Δ_rc_i + Δ_extc_i = 0.

Abbreviation: d_trY

Reference: Gnaiger_1993_Pure Appl Chem

Application in respirometry

In typical liquid phase reactions the volume of the system does not change during the reaction. When oxygen consumption (ν_O2 = -1 in the chemical reaction) is measured in aqueous solution, then the volume-specific oxygen flux is the time derivative of the advancement of the reaction per volume [1], J_V,O2 = d_rY_O2/dt = d_rξ_O2/dt∙V^-1 [(mol∙s­^-1)∙L­^-1]. The rate of O₂ concentration change is dc_O2/dt [(mol∙L­^-1)∙s­^-1], where concentration is c_O2 = n_O2∙V^-1. There is a difference between (1) J_V,O2 [mol∙s­^-1∙L­^-1] and (2) rate of concentration change [mol∙L­^-1∙s­^-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].

MitoPedia concepts: Ergodynamics