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Molar Mass Calculator
Enter any chemical formula—such as H2O, CaCO3, H2SO4, or Al2(SO4)3—to calculate total molar mass in g/mol and view each element's atomic contribution.
Enter Chemical Formula
Elemental Composition & Molar Mass
Total Molar Mass
342.150 g/mol
Parsed Formula
Al2(SO4)3
| Element | Quantity | Atomic Mass | Contribution (% by Mass) |
|---|
How Molar Mass Is Calculated
To find the molar mass of a chemical compound, multiply the standard atomic weight of each element (from the IUPAC Periodic Table) by the number of atoms of that element present in one formula unit, then sum all contributions:
Molar Mass (g/mol) = Σ (Atom Count of Elementᵢ × Standard Atomic Mass of Elementᵢ)
Example: Aluminium Sulfate — Al2(SO4)3
- Aluminium (Al): 2 atoms × 26.982 g/mol = 53.964 g/mol
- Sulfur (S): 1 × 3 = 3 atoms × 32.060 g/mol = 96.180 g/mol
- Oxygen (O): 4 × 3 = 12 atoms × 15.999 g/mol = 191.988 g/mol
Total Molar Mass = 53.964 + 96.180 + 191.988 = 342.132 g/mol
Frequently Asked Questions
Type element symbols with proper capitalization followed by numbers for subscripts, and use standard parentheses for polyatomic groups—for example, H2O, CaCO3, H2SO4, or Al2(SO4)3.
In IUPAC chemical notation, a two-letter element symbol always has an uppercase first letter and a lowercase second letter. Thus "Co" is Cobalt (58.933 g/mol), whereas "CO" is Carbon Monoxide (1 Carbon + 1 Oxygen = 28.010 g/mol).
Yes. Use a period (.) or middle dot (·) to separate the salt from the water of crystallization, such as CuSO4.5H2O.
Molar mass is expressed in grams per mole (g/mol), which is numerically equal to the molecular weight in unified atomic mass units (u or Da).
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