Molecular Weight
| Formula / Notation | M_r = sum of atomic masses; relative molecular mass (dimensionless) |
|---|---|
| Also Known As | Molar mass (same magnitude, different units), relative molecular mass, formula weight, MW |
What is Molecular Weight?
The sum of the atomic weights of all atoms in a molecule, expressed in atomic mass units (amu) or g/mol. Equivalent to molar mass. Determined experimentally by mass spectrometry, osmometry, or other techniques. Used in stoichiometric and structural calculations.
Formula & Notation
Other Names / Synonyms: Molar mass (same magnitude, different units), relative molecular mass, formula weight, MW
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
The sum of the atomic weights of all atoms in a molecule, expressed in atomic mass units (amu) or g/mol. Equivalent to molar mass. Determined experimentally by mass spectrometry, osmometry, or other techniques. Used in stoichiometric and structural calculations.
Molecular weight is used in: all stoichiometric calculations, preparation of solutions, osmometry and cryoscopy (colligative property measurements of MW), gel filtration chromatography (separation by MW), SDS-PAGE (protein MW determination), and in polymer characterisation (MW distribution by GPC/SE…
No direct safety concern for the concept. Drugs have precise molecular weights that determine dosing calculations. For natural product compounds isolated from toxic sources, correct MW assignment (and therefore correct formula) is essential to ensure the correct compound has been identified.
The formula or notation for Molecular Weight is: M_r = sum of atomic masses; relative molecular mass (dimensionless)