Aquamolality: a useful concentration unit

Standard Volumetric Properties of Tetra-N-ethylglycoluril (Bicaret) in Ordinary and Heavy Water at Temperatures from (278.15 to 318.15) K and Ambient Pressure

“…All the isotopically distinguishable aqueous solutions were prepared by weighting under airtight conditions using an analytical balance (LLB-200G model, Russia) with an uncertainty of ± (5·10 –5 ) g. The bicaret content was expressed in the form of both molality, m /(mol·(kg H 2 O) −1 ), for protiated aqueous solutions only and aquamolality, c aqm,2 , for both isotopically distinguishable systems. c aqm,2 is defined by the number of moles of a solute per approximately 55.51 (more precisely, 55.50843) moles of D 2 O or H 2 O. ,, The factor of 55.51 being roughly equal to the number of H 2 O moles in 1 kg of water is introduced in order for c aqm,2 and m in aqueous (H 2 O) solutions to coincide numerically . Applying the c aqm,2 scale is necessary to allow the proper comparison of solution densities, ρ s , and apparent molar volumes of a solute, V ϕ,2 , at the same (rounded) concentrations in the presence of equal numbers of H 2 O and D 2 O molecules.…”