Molar mass of kaolinite (Al₂Si₂O₅(OH)₄)

The molar mass of kaolinite (Al₂Si₂O₅(OH)₄) is 258.156077 g/mol, summed from the IUPAC standard atomic weights of Al x 2, Si x 2, O x 9, H x 4.

Mass of sample

Amount of substance

mol

Molar mass

258.156 077g/mol

= Exact Molar mass of kaolinite

Moles in the sample mass: 0.038 736 256 mol
Mass of that amount of substance: 258.156 08
Molecules in the sample mass: 2.33275e+22

Show the working

Mass of sample = 10
Amount of substance = 1
Molar mass = 26.9815384*2 + 28.085*2 + 15.999*9 + 1.008*4 = 258.156
Moles in the sample mass = 10 / 258.156 = 0.038 736 3
Mass of that amount of substance = 1 * 258.156 = 258.156
Molecules in the sample mass = 0.038 736 3 * NA = 2.33275e+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.

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The formula

Molar mass = sum over elements of (atomic weight x number of atoms)
For Al₂Si₂O₅(OH)₄: 26.9815384 x 2 + 28.085 x 2 + 15.999 x 9 + 1.008 x 4 = 258.156077 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)	9	15.999	143.991	55.777 %
Silicon (Si)	2	28.085	56.17	21.758 %
Aluminium (Al)	2	26.9815384	53.963077	20.903 %
Hydrogen (H)	4	1.008	4.032	1.5618 %

Contributions add to the molar mass of 258.156077 g/mol. Atomic weights are the IUPAC 2021 standard values.

Frequently asked

What is the molar mass of kaolinite?

258.156077 g/mol, for the formula Al₂Si₂O₅(OH)₄.

How do you convert grams of kaolinite to moles?

Divide the mass in grams by 258.156077 g/mol. One gram of kaolinite is 0.00387363 mol.

How many grams are in one mole of kaolinite?

258.156077 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.