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Molar Mass, Molecular Weight and Elemental Composition Calculator

Molar mass of HHeLiBeBCNOFNeSArUCe is 563.1275 g/mol

Convert between HHeLiBeBCNOFNeSArUCe weight and moles
CompoundMolesWeight, g
HHeLiBeBCNOFNeSArUCe

Elemental composition of HHeLiBeBCNOFNeSArUCe
ElementSymbolAtomic weightAtomsMass percent
HydrogenH1.0079410.1790
HeliumHe4.00260210.7108
LithiumLi6.94111.2326
BerylliumBe9.01218211.6004
BoronB10.81111.9198
CarbonC12.010712.1329
NitrogenN14.006712.4873
OxygenO15.999412.8412
FluorineF18.998403213.3737
NeonNe20.179713.5835
SulfurS32.06515.6941
ArgonAr39.94817.0940
UraniumU238.02891142.2691
CeriumCe140.116124.8818

Computing molar mass step by step

First, compute the number of each atom in HHeLiBeBCNOFNeSArUCe:
H: 1, He: 1, Li: 1, Be: 1, B: 1, C: 1, N: 1, O: 1, F: 1, Ne: 1, S: 1, Ar: 1, U: 1, Ce: 1

Then, lookup atomic weights for each element in periodic table:
H: 1.00794, He: 4.002602, Li: 6.941, Be: 9.012182, B: 10.811, C: 12.0107, N: 14.0067, O: 15.9994, F: 18.9984032, Ne: 20.1797, S: 32.065, Ar: 39.948, U: 238.02891, Ce: 140.116

Now, compute the sum of products of number of atoms to the atomic weight:
Molar mass (HHeLiBeBCNOFNeSArUCe) = ∑ Counti * Weighti =
Count(H) * Weight(H) + Count(He) * Weight(He) + Count(Li) * Weight(Li) + Count(Be) * Weight(Be) + Count(B) * Weight(B) + Count(C) * Weight(C) + Count(N) * Weight(N) + Count(O) * Weight(O) + Count(F) * Weight(F) + Count(Ne) * Weight(Ne) + Count(S) * Weight(S) + Count(Ar) * Weight(Ar) + Count(U) * Weight(U) + Count(Ce) * Weight(Ce) =
1 * 1.00794 + 1 * 4.002602 + 1 * 6.941 + 1 * 9.012182 + 1 * 10.811 + 1 * 12.0107 + 1 * 14.0067 + 1 * 15.9994 + 1 * 18.9984032 + 1 * 20.1797 + 1 * 32.065 + 1 * 39.948 + 1 * 238.02891 + 1 * 140.116 =
563.1275 g/mol


Mass percent compositionAtomic percent composition

Formula in Hill system is CHArBBeCeFHeLiNNeOSU

Computing molar mass (molar weight)

To calculate molar mass of a chemical compound enter its formula and click 'Compute'. In chemical formula you may use:
  • Any chemical element. Capitalize the first letter in chemical symbol and use lower case for the remaining letters: Ca, Fe, Mg, Mn, S, O, H, C, N, Na, K, Cl, Al.
  • Functional groups: D, T, Ph, Me, Et, Bu, AcAc, For, Tos, Bz, TMS, tBu, Bzl, Bn, Dmg
  • parenthesis () or brackets [].
  • Common compound names.
Examples of molar mass computations: NaCl, Ca(OH)2, K4[Fe(CN)6], CuSO4*5H2O, nitric acid, potassium permanganate, ethanol, fructose, caffeine, water.

Molar mass calculator also displays common compound name, Hill formula, elemental composition, mass percent composition, atomic percent compositions and allows to convert from weight to number of moles and vice versa.

Computing molecular weight (molecular mass)

To calculate molecular weight of a chemical compound enter it's formula, specify its isotope mass number after each element in square brackets.
Examples of molecular weight computations: C[14]O[16]2, S[34]O[16]2.

Definitions

  • Molecular mass (molecular weight) is the mass of one molecule of a substance and is expressed in the unified atomic mass units (u). (1 u is equal to 1/12 the mass of one atom of carbon-12)
  • Molar mass (molar weight) is the mass of one mole of a substance and is expressed in g/mol.
  • Mole is a standard scientific unit for measuring large quantities of very small entities such as atoms and molecules. One mole contains exactly 6.022 ×1023 particles (Avogadro's number)

Steps to calculate molar mass

  1. Identify the compound: write down the chemical formula of the compound. For example, water is H2O, meaning it contains two hydrogen atoms and one oxygen atom.
  2. Find atomic masses: look up the atomic masses of each element present in the compound. The atomic mass is usually found on the periodic table and is given in atomic mass units (amu).
  3. Calculate molar mass of each element: multiply the atomic mass of each element by the number of atoms of that element in the compound.
  4. Add them together: add the results from step 3 to get the total molar mass of the compound.

Example: calculating molar mass

Let's calculate the molar mass of carbon dioxide (CO2):

  • Carbon (C) has an atomic mass of about 12.01 amu.
  • Oxygen (O) has an atomic mass of about 16.00 amu.
  • CO2 has one carbon atom and two oxygen atoms.
  • The molar mass of carbon dioxide is 12.01 + (2 × 16.00) = 44.01 g/mol.

Lesson on computing molar mass

Weights of atoms and isotopes are from NIST article.

Related: Molecular weights of amino acids

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