98.072
g/mol
1.0197
mol
6.14
x10^23
98.072
g/mol
1.0197
mol
6.14
x10^23
The Molar Mass Calculator determines the molar mass of a chemical compound and converts a given sample mass to moles and number of molecules. Molar mass is the mass of one mole of a substance, measured in grams per mole (g/mol), and serves as the essential bridge between the atomic world and laboratory measurements. By entering the atomic masses and counts for up to three elements, plus an optional sample mass, this calculator provides the molar mass, the number of moles in your sample, and the approximate number of molecules. This tool is indispensable for stoichiometry, solution preparation, and any quantitative chemical analysis. Whether you are preparing reagent solutions or calculating reaction yields, accurate molar mass values form the foundation of your calculations.
The molar mass is calculated identically to molecular weight:
M = sum(A_i x n_i)
Where A_i is the atomic mass of element i in g/mol and n_i is the number of atoms in the formula. Once the molar mass M is known, two additional conversions are performed:
Avogadro's number was originally determined by multiple independent methods including X-ray crystallography of silicon spheres, Brownian motion measurements, and electrolysis experiments. Its current NIST value is exactly 6.02214076 x 10^23 mol^-1 as redefined in 2019.
For the molecules output, the result is displayed in units of 10^23 for readability. Multiply by 10^23 to get the actual number of molecules. For ionic compounds, the count represents formula units rather than molecules.
The molar mass tells you how many grams of compound you need to weigh out to have exactly one mole. The moles value shows how many moles are present in your specified sample mass, which is needed for stoichiometric calculations and molarity determinations. The molecule count, expressed in units of 10^23, gives you a sense of the enormous number of particles even in small laboratory quantities. For context, one mole of water (18 grams) contains 6.022 x 10^23 molecules, more than the estimated number of stars in the observable universe.
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Results
Sulfuric acid H2SO4 has a molar mass of 98.072 g/mol. A 100g sample contains about 1.02 moles, which equals approximately 6.14 x 10^23 molecules. This is the most widely produced chemical in the world by mass.
Inputs
Results
Ethanol (C2H6O) has a molar mass of 46.069 g/mol. A 46g sample is very close to exactly one mole, containing approximately 6.01 x 10^23 molecules. This demonstrates how molar mass provides a direct link between grams and moles.
They are numerically identical but use different units. Molar mass is expressed in grams per mole (g/mol) and refers to a macroscopic quantity (one mole). Molecular weight is in atomic mass units (amu) and refers to a single molecule. The numerical value is the same because the amu and g/mol scales are defined relative to the same standard (carbon-12).
Avogadro's number (6.022 x 10^23) bridges the enormous gap between atomic-scale masses (10^-24 to 10^-22 grams per atom) and laboratory-scale masses (grams). It was chosen so that 1 mole of carbon-12 atoms has a mass of exactly 12 grams, making the g/mol and amu scales numerically equivalent.
For compounds with more than 3 elements, you can calculate the contribution of the first 3 elements, note the subtotal, then calculate the remaining elements separately and add the results. Alternatively, combine elements with similar masses or calculate the full formula in stages.
A formula unit is the simplest whole-number ratio of ions in an ionic compound. Since ionic compounds form crystal lattices rather than discrete molecules, we use formula units instead of molecules. For NaCl, one formula unit consists of one Na+ ion and one Cl- ion. The molar mass of a formula unit is calculated the same way as molecular weight.
Molar mass calculations are as accurate as the atomic masses used. IUPAC standard atomic weights are given to 3-5 significant figures for most elements, yielding molar masses accurate to about 0.01-0.001 g/mol. For most laboratory work, 3-4 significant figures are sufficient.
The standard atomic weight of an element can change slightly as IUPAC periodically updates values based on new measurements of isotopic abundances. For example, the atomic weight of argon was updated in 2017. However, these changes are typically very small and rarely affect routine calculations.
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