Title: fractional change of a quantity
Long Title: IUPAC Gold Book - fractional change of a quantity
DOI: 10.1351/goldbook.F02495
Status: current

Definition
A term which may be expressed infinitesimally at time \(t\) by the differential \(\frac{\rm{d}Q(t)}{Q(t)}\). For a finite time interval the quotient is \[\frac{\Delta Q\left(t_{1};t_{2}\right)}{Q\left(t_{1}\right)} = \frac{\left[Q\left(t_{2}\right)\,-\,Q\left(t_{1}\right)\right]}{Q\left(t_{1}\right)}\] The quantities \(Q(t_{1})\) and \(Q(t_{2})\) are of the same kind and have the same type of component. Fractional change has dimension one. Examples are: mass fractional change, \(\frac{\rm{d}m(t)}{m(t)}\); amount of substance fractional change, \(\frac{\rm{d}n(t)}{n(t)}\).

Related Term
- amount of substance: https://goldbook.iupac.org//terms/view/A00297

Source
- PAC, 1992, 64, 1569. 'Quantities and units for metabolic processes as a function of time (IUPAC Recommendations 1992)' on page 1571 (https://doi.org/10.1351/pac199264101569)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/F02495/html
- json: https://goldbook.iupac.org/terms/view/F02495/json
- xml: https://goldbook.iupac.org/terms/view/F02495/xml

Citation: Citation: 'fractional change of a quantity' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.F02495
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Accessed: 2026-04-19T04:07:55+00:00