Molar Mass Calculator
The molar mass of sulfuric acid H2SO4 is 98.072 g/mol: two hydrogens, one sulfur and four oxygens, from IUPAC atomic weights.
Case matters: Co is cobalt, CO is carbon monoxide. Brackets and hydrates work: Ca(OH)2, CuSO4·5H2O, K4[Fe(CN)6].
98.072 g/mol
Full answer, then cut to fewer decimals (not rounded):
- 98.072 g/mol
- 98.07 g/mol
- 98.0 g/mol
- Mass of one molecule M/Nₐ
- 1.628523874 × 10⁻²² g
- Moles in 100 g
- 1.019659026 mol
| Element | Atoms | Atomic weight | Mass (g/mol) | Mass % |
|---|---|---|---|---|
| H | 2 | 1.008 | 2.016 | 2.05563 |
| S | 1 | 32.06 | 32.06 | 32.6903 |
| O | 4 | 15.999 | 63.996 | 65.2541 |
Step-by-step solution
- M = 2 × 1.008 (H) + 1 × 32.06 (S) + 4 × 15.999 (O)
- M = 2.016 + 32.06 + 63.996
- M = 98.072 g/mol
Molar Mass Formula
M = Σ nᵢ Aᵢ
nᵢ number of atoms of each element, Aᵢ its standard atomic weight (g/mol)
Worked Example
Sulfuric acid, H2SO4:
- M = 2 × 1.008 (H) + 1 × 32.06 (S) + 4 × 15.999 (O)
- M = 2.016 + 32.06 + 63.996
- M = 98.072 g/mol
Moles in 100 g: 1.019659026 mol
| Element | Atoms | Atomic weight | Mass (g/mol) | Mass % |
|---|---|---|---|---|
| H | 2 | 1.008 | 2.016 | 2.05563 |
| S | 1 | 32.06 | 32.06 | 32.6903 |
| O | 4 | 15.999 | 63.996 | 65.2541 |
Atomic weights used
Abridged standard atomic weights from IUPAC (CIAAW 2021), e.g. H 1.008, C 12.011, N 14.007, O 15.999, Na 22.990, Cl 35.45. Elements with no stable isotopes use the mass number of their longest-lived isotope.
More Moles and Concentration Calculators
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Moles Calculator
n = m / M
n amount (mol), m mass (g), M molar mass (g/mol); particles N = n × Nₐ
Example: 36.03 g of water (M = 18.015 g/mol): Amount of substance n = 2 mol.
-
Molarity Calculator
c = m / (M × V)
c molarity (mol/L), m mass of solute (g), M molar mass (g/mol), V volume of solution (L)
Example: 29.22 g of sodium chloride (M = 58.44 g/mol) made up to 1 litre: Molarity c = 0.5 mol/L (M).
-
Dilution Calculator
C₁ V₁ = C₂ V₂
C₁ stock concentration, V₁ stock volume, C₂ final concentration, V₂ final volume
Example: Making 1 L of 0.1 M solution from a 2 M stock: Stock volume needed V₁ = 0.05 L.
Frequently asked questions
Why does my textbook give 98.079 g/mol?
Older tables list sulfur as 32.065; IUPAC now gives the abridged value 32.06 because natural sulfur varies. Differences in the third decimal come from the table used, not the method.
How do I enter hydrates and brackets?
Write CuSO4·5H2O (or CuSO4*5H2O or CuSO4.5H2O) for hydrates, and use ( ) or [ ] for groups: Al2(SO4)3, K4[Fe(CN)6].
Is molar mass the same as molecular weight?
Numerically yes: molar mass in g/mol equals the relative molecular mass, which has no unit, and the mass of one molecule in daltons.
Sources
- Standard Atomic Weights (abridged values), IUPAC Commission on Isotopic Abundances and Atomic Weights, IUPAC CIAAW .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
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APA
Scientific Converters. (2026, October 15). Molar Mass Calculator. Retrieved October 25, 2026, from https://scientificconverters.com/calculators/molar-mass-calculator/
IEEE
Scientific Converters, "Molar Mass Calculator," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/calculators/molar-mass-calculator/