The rate of conversion for a reaction occurring in a closed system is defined as the time derivative of the @E02283@: \[\overset{\text{.}}{\xi }=\frac{\mathrm{d}\xi }{\mathrm{d}t}\] In view of the definition of @E02283@ it follows that with reference to any species in a reaction showing time-independent @S06026@ \[\overset{\text{.}}{\xi }=\frac{\mathrm{d}\xi }{\mathrm{d}t}=\frac{1}{\nu _{i}}\ \frac{\mathrm{d}n_{i}}{\mathrm{d}t}\] where \(n_{i}\) is the amount of the species at any time and \(\nu _{i}\) is its @S06021@ @C01124@.