Molecular weight

Molecular weight
Molecular Mo*lec"u*lar, a. [Cf. F. mol['e]culare. See {Molecule}.] (Phys. & Chem.) Pertaining to, connected with, produced by, or consisting of, molecules; as, molecular forces; molecular groups of atoms, etc. [1913 Webster]

{Molecular attraction} (Phys.), attraction acting between the molecules of bodies, and at insensible distances.

{Molecular weight} (Chem.), the weight of a molecule of any gas or vapor as compared with the hydrogen atom having weight of 1 as a standard; the sum of the atomic weights of the constituents of a molecule; thus, the molecular weight of water ({H2O}) is 18. For more precise measurements, the weight of the carbon isotope carbon-12 is used as the standard, that isotope having the value of 12.000. In this systen, now used almost universally, the hydrogen atom has a weight of 1.0079. [1913 Webster +PJC]


The Collaborative International Dictionary of English. 2000.

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  • molecular weight — n the mass of a molecule that may be calculated as the sum of the atomic weights of its constituent atoms * * * the weight of a molecule of a substance as compared with that of an atom of carbon 12; it is equal to the sum of the atomic weights of …   Medical dictionary

  • molecular weight — n. the relative average weight of a molecule of a substance, expressed by a number equal to the sum of the atomic weights of all atoms in the molecule …   English World dictionary

  • molecular weight — Chem. the average weight of a molecule of an element or compound measured in units once based on the weight of one hydrogen atom taken as the standard or on 1/16 the weight of an oxygen atom, but after 1961 based on 1/12 the weight of the carbon… …   Universalium

  • molecular weight — UK / US noun [countable/uncountable] Word forms molecular weight : singular molecular weight plural molecular weights science the total of the atomic weights of all the elements in a compound …   English dictionary

  • molecular weight — santykinė molekulinė masė statusas T sritis Standartizacija ir metrologija apibrėžtis Molekulės vidutinės masės arba tiksliai apibrėžto medžiagos darinio masės ir nuklido ¹²C atomo masės 1/12 dalies dalmuo. atitikmenys: angl. molecular mass;… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • molecular weight — santykinė molekulinė masė statusas T sritis Standartizacija ir metrologija apibrėžtis Molekulę sudarančių atomų santykinių atominių masių suma, skaitine verte lygi medžiagos molio masei. atitikmenys: angl. molecular mass; molecular weight;… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • molecular weight — santykinė molekulinė masė statusas T sritis chemija apibrėžtis Molekulę sudarančių atomų santykinių atominių masių suma, skaitine verte lygi vieno medžiagos molio masei. atitikmenys: angl. molecular mass; molecular weight; relative molecular mass …   Chemijos terminų aiškinamasis žodynas

  • molecular weight — (MW)    The sum of the atomic weights of all of the atoms within a molecule. Generally, molecules of the same type have higher boiling points if the molecular weight is higher …   Forensic science glossary

  • Molecular Weight Cut Off — or MWCO refers to the lowest molecular weight solute (in Daltons) in which 90% of the solute is retained by the membrane[1], or the molecular weight of the molecule (e.g. globular protein) that is 90% retained by the membrane.[2] This definition… …   Wikipedia

  • molecular weight — weight of a molecule …   English contemporary dictionary

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