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molecular weight

noun, Chemistry
1.
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 (0.0625) the weight of an oxygen atom, but after 1961 based on 1/12 (0.083) the weight of the carbon-12 atom; the sum of the atomic weights of all the atoms in a molecule.
Abbreviation: mol. wt.
Also called formula weight.
Origin
1875-1880
1875-80
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for molecular weight
  • The first instrument separates all the components of the mixture and the other measures the molecular weight of each.
  • We also wanted to understand how the molecular weight changed as a function of our salt concentration.
  • Natural gas forms when the temperature is higher, favoring lighter molecular weight alkanes.
  • One compound is of low molecular weight and another of high molecular weight.
British Dictionary definitions for molecular weight

molecular weight

noun
1.
the former name for relative molecular mass
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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molecular weight in Medicine

molecular weight n.
Abbr. mol wt, MW
The sum of the atomic weights of all the atoms in a molecule. Also called formula weight.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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molecular weight in Science
molecular weight  
The sum of the atomic weights of the atoms contained in a molecule. Also called relative molecular mass.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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molecular weight in Culture
molecular weight [(muh-lek-yuh-luhr)]

The sum of the atomic weights of all the atoms in a molecule.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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13
18
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