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The Dumas method of molecular weight determination was historically a procedure used to determine the molecular weight of an unknown volatile substance. [1][2] The method was designed by the French chemist Jean Baptiste André Dumas, after whom the procedure is now named. Dumas used the method to determine the vapour densities of elements ...
M N−1. In chemistry, the molar mass (M) (sometimes called molecular weight or formula weight, but see related quantities for usage) of a chemical compound is defined as the ratio between the mass and the amount of substance (measured in moles) of any sample of the compound. [1] The molar mass is a bulk, not molecular, property of a substance.
The Dumas method has the advantages of being easy to use and fully automatable. It has been developed into a considerably faster method than the Kjeldahl method, and can take a few minutes per measurement, as compared to the hour or more for Kjeldahl. It also does not make use of toxic chemicals or catalysts. One major disadvantage is its high ...
Equivalent weights may be calculated from molar masses if the chemistry of the substance is well known: sulfuric acid has a molar mass of 98.078(5) g mol −1, and supplies two moles of hydrogen ions per mole of sulfuric acid, so its equivalent weight is 98.078(5) g mol −1 /2 eq mol −1 = 49.039(3) g eq −1.
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.
Stoichiometry. A stoichiometric diagram of the combustion reaction of methane. Stoichiometry (/ ˌstɔɪkiˈɒmɪtri /) is the relationships among the weights of reactants and products before, during, and following chemical reactions. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the ...
Molar volume. In chemistry and related fields, the molar volume, symbol Vm, [1] or of a substance is the ratio of the volume (V) occupied by a substance to the amount of substance (n), usually at a given temperature and pressure. It is also equal to the molar mass (M) divided by the mass density (ρ): The molar volume has the SI unit of cubic ...
In thermodynamics, the cryoscopic constant, Kf, relates molality to freezing point depression (which is a colligative property). It is the ratio of the latter to the former: b is the molality of the solution. Through cryoscopy, a known constant can be used to calculate an unknown molar mass. The term "cryoscopy" means "freezing measurement" in ...