Molar mass of paracetamol (C₈H₉NO₂)

The molar mass of paracetamol (C₈H₉NO₂) is 151.165 g/mol, summed from the IUPAC standard atomic weights of C x 8, H x 9, N, O x 2.

Mass of sample

Amount of substance

mol

Molar mass

151.165g/mol

= Exact Molar mass of paracetamol

Moles in the sample mass: 0.066 152 879 mol
Mass of that amount of substance: 151.165
Molecules in the sample mass: 3.98382e+22

Show the working

Mass of sample = 10
Amount of substance = 1
Molar mass = 12.011*8 + 1.008*9 + 14.007 + 15.999*2 = 151.165
Moles in the sample mass = 10 / 151.165 = 0.066 152 9
Mass of that amount of substance = 1 * 151.165 = 151.165
Molecules in the sample mass = 0.066 152 9 * NA = 3.98382e+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 C₈H₉NO₂: 12.011 x 8 + 1.008 x 9 + 14.007 + 15.999 x 2 = 151.165 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)	8	12.011	96.088	63.565 %
Oxygen (O)	2	15.999	31.998	21.168 %
Nitrogen (N)	1	14.007	14.007	9.266 %
Hydrogen (H)	9	1.008	9.072	6.0014 %

Contributions add to the molar mass of 151.165 g/mol. Atomic weights are the IUPAC 2021 standard values.

Frequently asked

What is the molar mass of paracetamol?

151.165 g/mol, for the formula C₈H₉NO₂.

How do you convert grams of paracetamol to moles?

Divide the mass in grams by 151.165 g/mol. One gram of paracetamol is 0.00661529 mol.

How many grams are in one mole of paracetamol?

151.165 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.