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The molar mass is defined as the mass of a given substance divided by the amount of the substance, and is expressed in grams per mol (g/mol). That makes the molar mass an average of many particles or molecules (potentially containing different isotopes), and the molecular mass the mass of one specific particle or molecule. The molar mass is ...
This, together with the measured density ρ of the sample, allows the molar volume V m to be determined: =, where M u is the molar mass constant. The CODATA value for the molar volume of silicon is 1.205 883 199 (60) × 10 −5 m 3 ⋅mol −1 , with a relative standard uncertainty of 4.9 × 10 −8 .
The molar mass of atoms of an element is given by the relative atomic mass of the element multiplied by the molar mass constant, M u ≈ 1.000 000 × 10 −3 kg/mol ≈ 1 g/mol. For normal samples from Earth with typical isotope composition, the atomic weight can be approximated by the standard atomic weight [ 2 ] or the conventional atomic weight.
The term molality is formed in analogy to molarity which is the molar concentration of a solution. The earliest known use of the intensive property molality and of its adjectival unit, the now-deprecated molal, appears to have been published by G. N. Lewis and M. Randall in the 1923 publication of Thermodynamics and the Free Energies of Chemical Substances. [3]
The bulk volume of a material —inclusive of the void space fraction— is often obtained by a simple measurement (e.g. with a calibrated measuring cup) or geometrically from known dimensions. Mass divided by bulk volume determines bulk density. This is not the same thing as the material volumetric mass density.
ρ new is the unknown density of the new (green) liquid. RD new/ref is the relative density of the new liquid with respect to the reference. V is the volume of reference liquid displaced, i.e. the red volume in the diagram. m is the mass of the entire hydrometer. g is the local gravitational constant. Δx is the change in displacement.
A density meter (densimeter) is a device which measures the density of an object or material. Density is usually abbreviated as either ρ {\displaystyle \rho } or D {\displaystyle D} . Typically, density either has the units of k g / m 3 {\displaystyle kg/m^{3}} or l b / f t 3 {\displaystyle lb/ft^{3}} .
The simplest model of the dense fluid viscosity is a (truncated) power series of reduced mole density or pressure. Jossi et al. (1962) [14] presented such a model based on reduced mole density, but its most widespread form is the version proposed by Lohrenz et al. (1964) [15] which is displayed below.