Molar mass of urea (CH₄N₂O)
The molar mass of urea (CH₄N₂O) is 60.056 g/mol, summed from the IUPAC standard atomic weights of C, H x 4, N x 2, O. The most concentrated solid nitrogen fertiliser, at 46% N by mass.
- Moles in the sample mass
- 0.166 511 26 mol
- Mass of that amount of substance
- 60.056
- Molecules in the sample mass
- 1.00275e+23
Show the working
- Mass of sample = 10
- Amount of substance = 1
- Molar mass = 12.011 + 1.008*4 + 14.007*2 + 15.999 = 60.056
- Moles in the sample mass = 10 / 60.056 = 0.166 511
- Mass of that amount of substance = 1 * 60.056 = 60.056
- Molecules in the sample mass = 0.166 511 * NA = 1.00275e+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 CH₄N₂O: 12.011 + 1.008 x 4 + 14.007 x 2 + 15.999 = 60.056 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.
The most concentrated solid nitrogen fertiliser, at 46% N by mass.
Composition by mass
| Element | Atoms | Atomic weight | Contribution (g/mol) | Share of mass |
|---|---|---|---|---|
| Nitrogen (N) | 2 | 14.007 | 28.014 | 46.646 % |
| Oxygen (O) | 1 | 15.999 | 15.999 | 26.64 % |
| Carbon (C) | 1 | 12.011 | 12.011 | 20 % |
| Hydrogen (H) | 4 | 1.008 | 4.032 | 6.7137 % |
Contributions add to the molar mass of 60.056 g/mol. Atomic weights are the IUPAC 2021 standard values.
Frequently asked
What is the molar mass of urea?
60.056 g/mol, for the formula CH₄N₂O.
How do you convert grams of urea to moles?
Divide the mass in grams by 60.056 g/mol. One gram of urea is 0.0166511 mol.
How many grams are in one mole of urea?
60.056 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.