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Historically, the mole was defined as the amount of substance in 12 grams of the carbon-12 isotope.As a consequence, the mass of one mole of a chemical compound, in grams, is numerically equal (for all practical purposes) to the mass of one molecule or formula unit of the compound, in daltons, and the molar mass of an isotope in grams per mole is approximately equal to the mass number ...
Since 2019, a mole of any substance has been redefined in the SI as the amount of that substance containing an exactly defined number of particles, 6.022 140 76 × 10 23. The molar mass of a compound in g/mol thus is equal to the mass of this number of molecules of the compound in grams.
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 ...
The number of molecules per mole in a substance is given by the Avogadro constant, exactly 6.022 140 76 × 10 23 mol −1 since the 2019 revision of the SI. Thus, to calculate the stoichiometry by mass, the number of molecules required for each reactant is expressed in moles and multiplied by the molar mass of each to give the mass of each ...
The equivalent weight of an element is the mass which combines with or displaces 1.008 gram of hydrogen or 8.0 grams of oxygen or 35.5 grams of chlorine. The equivalent weight of an element is the mass of a mole of the element divided by the element's valence. That is, in grams, the atomic weight of the element divided by the usual valence. [2]
The number of particles in a mole is the Avogadro number (symbol N 0) and the numerical value of the Avogadro constant (symbol N A) expressed in mol −1. [1] 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 ...
1 pound (lb) = 16 ounces (oz) 1 kilogram (kg) = 1,000 grams (g) = 2.20462262 lb 1 lb = 453.59237 g = 0.45359237 kg 1 oz = 28.3495231 g. In four different English-language countries of recipe and measuring-utensil markets, approximate cup volumes range from 236.59 to 284.1 milliliters (mL).
Mole fraction is numerically identical to the number fraction, which is defined as the number of particles of a constituent N i divided by the total number of all molecules N tot. Whereas mole fraction is a ratio of amounts to amounts (in units of moles per moles), molar concentration is a quotient of amount to volume (in units of moles per litre).