https://doi.org/10.1351/goldbook.R05152
Like the
rate of consumption
, the rate of formation of a specified product may be defined in two ways: - As the time derivative of the amount of a product. Thus for a product Y, present at any time in amount
. the rate of its formation may be given by: This definition is particularly appropriate for open systems. - For kinetics in closed systems it is more usual to define a rate of formation per unit volume, denoted
: When the volume is constant this reduces to: When the volume is not constant the relationship may be differentiated to give: and the rate of formation becomes: A rate of formation may be specified even for a reaction of time dependentstoichiometryor of unknownstoichiometry.