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. : mol. wt.

molecular weight

noun

1. the former name for relative molecular mass

molecular weight

1. The sum of the atomic weights of the atoms contained in a molecule.
2. Also called relative molecular mass

molecular weight

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

Word History and Origins

Origin of molecular weight¹

First recorded in 1875–80

Example Sentences

The molecular weight of alcohol in dilute aqueous solution is the same as in vapor form.

From Project Gutenberg

Hence the number of grams of a given substance in a liter divided by its molecular weight represents its concentration.

From Project Gutenberg

Cryoscopic determinations of its molecular weight show that it is H2O2.

From Project Gutenberg

The molecular weight is the sum of the atomic weights of the group.

From Project Gutenberg

Acids like sulphuric acid are termed bibasic, and their equivalent is only half the molecular weight.

From Project Gutenberg