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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]
In chemistry, the mass concentration ρ i (or γ i) is defined as the mass of a constituent m i divided by the volume of the mixture V. [1]= For a pure chemical the mass concentration equals its density (mass divided by volume); thus the mass concentration of a component in a mixture can be called the density of a component in a mixture.
The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.
If a molecule or salt dissociates in solution, the concentration refers to the original chemical formula in solution, the molar concentration is sometimes called formal concentration or formality (F A) or analytical concentration (c A). For example, if a sodium carbonate solution (Na 2 CO 3) has a formal concentration of c(Na 2 CO 3) = 1 mol/L ...
For example, the mass of water might be written in subscripts as m H 2 O, m water, m aq, m w (if clear from context) etc., or simply as m(H 2 O). Another example could be the electronegativity of the fluorine-fluorine covalent bond, which might be written with subscripts χ F-F, χ FF or χ F-F etc., or brackets χ(F-F), χ(FF) etc. Neither is ...
This principle is included in the ideal gas equation: =, where n is the amount of substance. The vapour density (ρ) is given by =. Combining these two equations gives an expression for the molar mass in terms of the vapour density for conditions of known pressure and temperature:
The SI value of the mole was chosen on the basis of the historical definition of the mole as the amount of substance that corresponds to the number of atoms in 12 grams of 12 C, [1] which made the mass of a mole of a compound expressed in grams, numerically equal to the average molecular mass or formula mass of the compound expressed in daltons.
The ideal gas equation can be rearranged to give an expression for the molar volume of an ideal gas: = = Hence, for a given temperature and pressure, the molar volume is the same for all ideal gases and is based on the gas constant: R = 8.314 462 618 153 24 m 3 ⋅Pa⋅K −1 ⋅mol −1, or about 8.205 736 608 095 96 × 10 −5 m 3 ⋅atm⋅K ...