mean substance rate, ΔnΔt 

https://doi.org/10.1351/goldbook.M03786
The amount of substance of a specified component changed in or moved to or from a system divided by the time during which the component was changed or moved. This kind of quantity usually should be preferred to mean mass rate or mean volume rate.
Source:
PAC, 1979, 51, 2451. (Quantities and Units in Clinical Chemistry) on page 2475 [Terms] [Paper]
Citation: 'mean substance rate' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.M03786 RIS BibTex EndNote
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Last revised: February 24, 2014