Molar mass of acetone (C₃H₆O)

The molar mass of acetone (C₃H₆O) is 58.08 g/mol, summed from the IUPAC standard atomic weights of C x 3, H x 6, O.

Mass of sample

Amount of substance

mol

Molar mass

58.08g/mol

= Exact Molar mass of acetone

Moles in the sample mass: 0.172 176 31 mol
Mass of that amount of substance: 58.08
Molecules in the sample mass: 1.03687e+23

Show the working

Mass of sample = 10
Amount of substance = 1
Molar mass = 12.011*3 + 1.008*6 + 15.999 = 58.08
Moles in the sample mass = 10 / 58.08 = 0.172 176
Mass of that amount of substance = 1 * 58.08 = 58.08
Molecules in the sample mass = 0.172 176 * NA = 1.03687e+23

Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.

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The formula

Molar mass = sum over elements of (atomic weight x number of atoms)
For C₃H₆O: 12.011 x 3 + 1.008 x 6 + 15.999 = 58.08 g/mol
Moles = mass / molar mass; mass = moles x molar mass
Molecules = moles x 6.02214076 x 10^23 (the Avogadro constant, exact by definition)

Molar mass in grams per mole is numerically equal to the molecular mass in daltons, so this figure doubles as the molecular weight.

Atomic weights are the IUPAC 2021 standard values. Several elements have a range rather than a single value because isotope ratios vary between sources; the conventional single value is used here.

Composition by mass

Element	Atoms	Atomic weight	Contribution (g/mol)	Share of mass
Carbon (C)	3	12.011	36.033	62.04 %
Oxygen (O)	1	15.999	15.999	27.546 %
Hydrogen (H)	6	1.008	6.048	10.413 %

Contributions add to the molar mass of 58.08 g/mol. Atomic weights are the IUPAC 2021 standard values.

Frequently asked

What is the molar mass of acetone?

58.08 g/mol, for the formula C₃H₆O.

How do you convert grams of acetone to moles?

Divide the mass in grams by 58.08 g/mol. One gram of acetone is 0.0172176 mol.

How many grams are in one mole of acetone?

58.08 g, by definition of the molar mass.

Is molar mass the same as molecular weight?

Numerically yes, for the purposes of this calculation. Molecular weight is a dimensionless ratio and molar mass carries units of g/mol, but the digits are identical.

Where the numbers come from

IUPAC 2021 standard atomic weights; Avogadro constant fixed by the 2019 SI.