Molar mass of calcium sulfate (CaSO₄)

The molar mass of calcium sulfate (CaSO₄) is 136.134 g/mol, summed from the IUPAC standard atomic weights of Ca, S, O x 4.

Mass of sample

Amount of substance

mol

Molar mass

136.134g/mol

= Exact Molar mass of calcium sulfate

Moles in the sample mass: 0.073 457 035 mol
Mass of that amount of substance: 136.134
Molecules in the sample mass: 4.42369e+22

Show the working

Mass of sample = 10
Amount of substance = 1
Molar mass = 40.078 + 32.06 + 15.999*4 = 136.134
Moles in the sample mass = 10 / 136.134 = 0.073 457
Mass of that amount of substance = 1 * 136.134 = 136.134
Molecules in the sample mass = 0.073 457 * NA = 4.42369e+22

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

Scenarios & local history

Compare a saved scenario

Recent calculations

The formula

Molar mass = sum over elements of (atomic weight x number of atoms)
For CaSO₄: 40.078 + 32.06 + 15.999 x 4 = 136.134 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
Oxygen (O)	4	15.999	63.996	47.01 %
Calcium (Ca)	1	40.078	40.078	29.44 %
Sulfur (S)	1	32.06	32.06	23.55 %

Contributions add to the molar mass of 136.134 g/mol. Atomic weights are the IUPAC 2021 standard values.

Frequently asked

What is the molar mass of calcium sulfate?

136.134 g/mol, for the formula CaSO₄.

How do you convert grams of calcium sulfate to moles?

Divide the mass in grams by 136.134 g/mol. One gram of calcium sulfate is 0.0073457 mol.

How many grams are in one mole of calcium sulfate?

136.134 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.