Moles from Mass
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Calculate molecular weight from chemical formulas
Use proper capitalization: Na, not NA or na
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Chemistry Fundamentals
Parse chemical formulas automatically and convert between mass and moles for lab, process, and educational use.
Core Relation
n = m / M
Unit
g / mol
Basis
IUPAC Atomic Masses
Use
Stoichiometry & Dosing
Reviewed by: CalculatorApp Chemistry & Engineering Team
Molar mass bridges atomic-scale chemistry and laboratory-scale measurements. It allows chemists and engineers to weigh out precise mole quantities for reactions, determine theoretical yields, prepare standard solutions, and connect mass data to structural molecular information. Accurate molar mass is fundamental to quantitative analytical chemistry.
Moles from Mass
n = m / MMass from Moles
m = n × MMolar Mass Sum
M = Σ(nᵢ × Aᵢ)Concentration Link
c = n / V| Compound Type | Molar Mass Range | Typical Field |
|---|---|---|
| Simple molecules (H₂O, CO₂) | 18–44 g/mol | Lab chemistry, gas behavior |
| Salts and ionic compounds | 50–400 g/mol | Solution prep, analytical chem |
| Organic compounds | Wide range | Pharmaceuticals, materials |
| Polymers | Very high (kDa+) | Materials science, coatings |
Early 1800s: Dalton develops atomic theory and relative atomic masses.
1811: Avogadro proposes equal volumes of gas contain equal molecules.
1860: Cannizzaro clarifies atomic and molecular weights at Karlsruhe congress.
1869: Mendeleev organizes elements by atomic mass in the periodic table.
1961: Carbon-12 standard adopted for atomic mass unit by IUPAC.
Modern era: High-resolution mass spectrometry enables ultra-precise molar mass measurement.
Chemical compound health and toxicology studies.
International chemical safety and risk guidance.
Toxicological profiles for industrial chemicals.
Pharmacological and biochemical clinical research.
Myth: Molar mass and molecular weight are totally different.
Fact: They are numerically identical but expressed in different units (g/mol vs u).
Myth: Subscript errors are minor.
Fact: A single subscript error changes the molar mass and invalidates all downstream calculations.
Myth: Isotopes do not affect molar mass.
Fact: Molar mass reflects natural isotopic abundance averages, not a single isotope.
Myth: Average atomic masses are arbitrary.
Fact: They are carefully maintained by IUPAC based on measured terrestrial isotopic abundances.
Molar mass is the mass per mole of a substance, expressed in grams per mole (g/mol).
Sum the atomic masses of all atoms in the formula, multiplied by their subscript quantities.
Molecular mass is in atomic mass units (u); molar mass is numerically equal but expressed in g/mol.
They are derived from isotopic abundances weighted by abundance fraction, published by IUPAC.
It converts between measurable mass and mole quantities essential for reaction calculations.
One mole contains 6.022 × 10²³ particles, linking molar mass to atomic-scale properties.
Parser handles standard chemical notation but verify unusual polyatomic or bracketed groups manually.
For repeating-unit polymers, calculate the monomer molar mass then scale by degree of polymerization.
In the ideal gas law, heavier molecules move slower at the same temperature (Maxwell-Boltzmann).
Precision is determined by atomic mass table accuracy and correct compound formula entry.
For mixtures, compute a mole-fraction-weighted average molar mass.
Solution preparation, reaction balancing, gas law calculations, analytical chemistry, and pharmaceutical dosing.
Connect molar mass with molarity, gas law, and thermodynamic calculators for complete quantitative work.
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