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Molar Mass, Molecular Weight and Elemental Composition Calculator

Molar mass of H2He2Li2Be2B2*C2N2O2F2Ne2Na2Mg2*3Al2Si2P2S2Cl2Ar2K2Ca2 is 1956.6274 g/mol

Convert between H2He2Li2Be2B2*C2N2O2F2Ne2Na2Mg2*3Al2Si2P2S2Cl2Ar2K2Ca2 weight and moles
CompoundMolesWeight, g
H2He2Li2Be2B2*C2N2O2F2Ne2Na2Mg2*3Al2Si2P2S2Cl2Ar2K2Ca2

Elemental composition of H2He2Li2Be2B2*C2N2O2F2Ne2Na2Mg2*3Al2Si2P2S2Cl2Ar2K2Ca2
ElementSymbolAtomic weightAtomsMass percent
HydrogenH1.0079420.1030
HeliumHe4.00260220.4091
LithiumLi6.94120.7095
BerylliumBe9.01218220.9212
BoronB10.81121.1051
CarbonC12.010721.2277
NitrogenN14.006721.4317
OxygenO15.999421.6354
FluorineF18.998403221.9420
NeonNe20.179722.0627
SodiumNa22.9897692822.3499
MagnesiumMg24.305022.4844
AluminumAl26.981538668.2739
SiliconSi28.085568.6124
PhosphorusP30.97376269.4981
SulfurS32.06569.8327
ChlorineCl35.453610.8717
ArgonAr39.948612.2501
PotassiumK39.0983611.9895
CalciumCa40.078612.2899

Computing molar mass step by step

First, compute the number of each atom in H2He2Li2Be2B2*C2N2O2F2Ne2Na2Mg2*3Al2Si2P2S2Cl2Ar2K2Ca2:
H: 2, He: 2, Li: 2, Be: 2, B: 2, C: 2, N: 2, O: 2, F: 2, Ne: 2, Na: 2, Mg: 2, Al: 6, Si: 6, P: 6, S: 6, Cl: 6, Ar: 6, K: 6, Ca: 6

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, Na: 22.98976928, Mg: 24.305, Al: 26.9815386, Si: 28.0855, P: 30.973762, S: 32.065, Cl: 35.453, Ar: 39.948, K: 39.0983, Ca: 40.078

Now, compute the sum of products of number of atoms to the atomic weight:
Molar mass (H2He2Li2Be2B2*C2N2O2F2Ne2Na2Mg2*3Al2Si2P2S2Cl2Ar2K2Ca2) = ∑ 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(Na) * Weight(Na) + Count(Mg) * Weight(Mg) + Count(Al) * Weight(Al) + Count(Si) * Weight(Si) + Count(P) * Weight(P) + Count(S) * Weight(S) + Count(Cl) * Weight(Cl) + Count(Ar) * Weight(Ar) + Count(K) * Weight(K) + Count(Ca) * Weight(Ca) =
2 * 1.00794 + 2 * 4.002602 + 2 * 6.941 + 2 * 9.012182 + 2 * 10.811 + 2 * 12.0107 + 2 * 14.0067 + 2 * 15.9994 + 2 * 18.9984032 + 2 * 20.1797 + 2 * 22.98976928 + 2 * 24.305 + 6 * 26.9815386 + 6 * 28.0855 + 6 * 30.973762 + 6 * 32.065 + 6 * 35.453 + 6 * 39.948 + 6 * 39.0983 + 6 * 40.078 =
1956.6274 g/mol


Mass percent compositionAtomic percent composition

Formula in Hill system is C2H2Al6Ar6B2Be2Ca6Cl6F2He2K6Li2Mg2N2Na2Ne2O2P6S6Si6

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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