Relative Molecular Mass
| Formula / Notation | Mr = Σ Ar |
|---|---|
| Also Known As | Molecular weight, Mr, formula weight (for ionic), molar mass (g/mol equivalent) |
What is Relative Molecular Mass?
The relative molecular mass (Mr, also called molecular weight) is the ratio of the average mass of a molecule to one-twelfth of the mass of a carbon-12 atom. It is calculated by summing the relative atomic masses of all atoms in the molecular formula. It is a dimensionless quantity and is numerically equal to the molar mass expressed in g/mol.
Formula & Notation
Other Names / Synonyms: Molecular weight, Mr, formula weight (for ionic), molar mass (g/mol equivalent)
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 relative molecular mass (Mr, also called molecular weight) is the ratio of the average mass of a molecule to one-twelfth of the mass of a carbon-12 atom. It is calculated by summing the relative atomic masses of all atoms in the molecular formula. It is a dimensionless quantity and is numerically equal to the molar mass expressed in g/mol.
Calculating moles from mass (n = m/Mr). Preparing solutions of known molarity. Stoichiometric calculations. Identifying compounds by mass spectrometry. Pharmaceutical dosing. Quality control of chemicals. Polymer molecular weight determination.
Theoretical concept — no direct safety concerns.
The formula or notation for Relative Molecular Mass is: Mr = Σ Ar