How this calculator works
Amount of substance counts specified entities. Choose molecules, atoms or formula units according to the material. One mole contains exactly 6.02214076 x 10^23 entities. A molecule count is not automatically an atom count: multiply by atoms per molecule for that conversion.
Formula
n = m(g)/M(g/mol); N = n x N_A; N_A = 6.02214076 x 10^23 mol^-1, exactly.
Worked example
0.5 mol contains 3.01107038 x 10^23 molecules. At 18.015 g/mol this amount has mass 9.0075 g.
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Frequently asked questions
Can I enter zero mass?
Zero mass gives zero moles when molar mass is known. Inferring molar mass requires positive mass and amount.
Does the calculation account for purity?
Use the mass of the substance of interest. Correct the weighed mass for purity separately.
Which atomic weights are appropriate?
Natural-isotope conventional atomic weights suit ordinary samples; enriched materials require isotope-specific molar mass.