Atomic Statement
In a closed, nonreacting blending system, mass and component amounts balance, but final liquid volume need not equal the sum of the starting volumes.
Principle
In a closed, nonreacting blending system, mass and component amounts balance, but final liquid volume need not equal the sum of the starting volumes.
Evidence And Locators
Brown chapters 1, 3 and 13; especially printed pp. 628–629. Ethanol–water volumetric data: https://trc.nist.gov/ThermoML/10.1016/j.fluid.2004.11.019.html
Application
Use mass fractions for exact mass accounting or label volume-weighted ABV as an estimate. Track losses and reference temperature separately.
Boundary
No chemistry model corrects an inaccurate pour or missing withdrawal. Conservation of each molecular species additionally requires no reaction.