Chemistry and laboratory
Grams to moles converter
Convert between grams, moles and number of particles for any formula or molar mass, using the exact Avogadro constant.
Runs in your browser. What you enter stays on this page and is not uploaded.
Result
- Mass
- 36.0 g
- Amount of substance
- 2.00 mol
- Particles (formula units)
- 1.20 × 10²⁴
- Atoms in total
- 3.61 × 10²⁴
- Molar mass used
- H₂O, 18.015 g/mol
Working
- n = m ÷ M = 36 g ÷ 18.015 g/mol = 2.00 mol
- N = n × NA = 1.99833 mol × 6.02214076 × 10²³ mol⁻¹ = 1.20 × 10²⁴
- Rounded to 3 significant figures. The Avogadro constant is exact (SI 2019).
Method and limits
Enter a substance and an amount in any unit; the other two quantities follow.
n = m ÷ M N = n × NA NA = 6.022 140 76 × 10²³ mol⁻¹ (exact)
The molar mass M comes from the formula using CIAAW 2024 abridged atomic weights, or from the number you type. Since 2019 the mole is defined by fixing the Avogadro constant exactly, so converting moles to particles adds no uncertainty. “Particles” means formula units: molecules for H2O, ion pairs for NaCl. For a formula the tool also counts atoms (particles × atoms per formula unit).
Answers keep the significant figures of the least precise number you enter (at least 3, at most 6); counts and coefficients are exact and do not limit precision.
Worked example
36.0 g of water: n = 36.0 g ÷ 18.015 g/mol = 2.00 mol, and N = 2.00 mol × 6.022 × 10²³ mol⁻¹ = 1.20 × 10²⁴ molecules (3.61 × 10²⁴ atoms).
References
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