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Molar Mass, Molecular Weight and Elemental Composition Calculator

Molar mass of O1N1He1Na1Fe1C1CU1Ga1F1H1B1SI1Cl1Ne1Ar1CN1CO1Ca1Rb1Mo1U1000Li1Au1Ag1Pt1 is 239541.2874 g/mol

Convert between O1N1He1Na1Fe1C1CU1Ga1F1H1B1SI1Cl1Ne1Ar1CN1CO1Ca1Rb1Mo1U1000Li1Au1Ag1Pt1 weight and moles
CompoundMolesWeight, g
O1N1He1Na1Fe1C1CU1Ga1F1H1B1SI1Cl1Ne1Ar1CN1CO1Ca1Rb1Mo1U1000Li1Au1Ag1Pt1

Elemental composition of O1N1He1Na1Fe1C1CU1Ga1F1H1B1SI1Cl1Ne1Ar1CN1CO1Ca1Rb1Mo1U1000Li1Au1Ag1Pt1
ElementSymbolAtomic weightAtomsMass percent
OxygenO15.999420.0134
NitrogenN14.006720.0117
HeliumHe4.00260210.0017
SodiumNa22.9897692810.0096
IronFe55.84510.0233
CarbonC12.010740.0201
UraniumU238.02891100199.4680
GalliumGa69.72310.0291
FluorineF18.998403210.0079
HydrogenH1.0079410.0004
BoronB10.81110.0045
SulfurS32.06510.0134
IodineI126.9044710.0530
ChlorineCl35.45310.0148
NeonNe20.179710.0084
ArgonAr39.94810.0167
CalciumCa40.07810.0167
RubidiumRb85.467810.0357
MolybdenumMo95.9610.0401
LithiumLi6.94110.0029
GoldAu196.96656910.0822
SilverAg107.868210.0450
PlatinumPt195.08410.0814

Computing molar mass step by step

First, compute the number of each atom in O1N1He1Na1Fe1C1CU1Ga1F1H1B1SI1Cl1Ne1Ar1CN1CO1Ca1Rb1Mo1U1000Li1Au1Ag1Pt1:
O: 2, N: 2, He: 1, Na: 1, Fe: 1, C: 4, U: 1001, Ga: 1, F: 1, H: 1, B: 1, S: 1, I: 1, Cl: 1, Ne: 1, Ar: 1, Ca: 1, Rb: 1, Mo: 1, Li: 1, Au: 1, Ag: 1, Pt: 1

Then, lookup atomic weights for each element in periodic table:
O: 15.9994, N: 14.0067, He: 4.002602, Na: 22.98976928, Fe: 55.845, C: 12.0107, U: 238.02891, Ga: 69.723, F: 18.9984032, H: 1.00794, B: 10.811, S: 32.065, I: 126.90447, Cl: 35.453, Ne: 20.1797, Ar: 39.948, Ca: 40.078, Rb: 85.4678, Mo: 95.96, Li: 6.941, Au: 196.966569, Ag: 107.8682, Pt: 195.084

Now, compute the sum of products of number of atoms to the atomic weight:
Molar mass (O1N1He1Na1Fe1C1CU1Ga1F1H1B1SI1Cl1Ne1Ar1CN1CO1Ca1Rb1Mo1U1000Li1Au1Ag1Pt1) = ∑ Counti * Weighti =
Count(O) * Weight(O) + Count(N) * Weight(N) + Count(He) * Weight(He) + Count(Na) * Weight(Na) + Count(Fe) * Weight(Fe) + Count(C) * Weight(C) + Count(U) * Weight(U) + Count(Ga) * Weight(Ga) + Count(F) * Weight(F) + Count(H) * Weight(H) + Count(B) * Weight(B) + Count(S) * Weight(S) + Count(I) * Weight(I) + Count(Cl) * Weight(Cl) + Count(Ne) * Weight(Ne) + Count(Ar) * Weight(Ar) + Count(Ca) * Weight(Ca) + Count(Rb) * Weight(Rb) + Count(Mo) * Weight(Mo) + Count(Li) * Weight(Li) + Count(Au) * Weight(Au) + Count(Ag) * Weight(Ag) + Count(Pt) * Weight(Pt) =
2 * 15.9994 + 2 * 14.0067 + 1 * 4.002602 + 1 * 22.98976928 + 1 * 55.845 + 4 * 12.0107 + 1001 * 238.02891 + 1 * 69.723 + 1 * 18.9984032 + 1 * 1.00794 + 1 * 10.811 + 1 * 32.065 + 1 * 126.90447 + 1 * 35.453 + 1 * 20.1797 + 1 * 39.948 + 1 * 40.078 + 1 * 85.4678 + 1 * 95.96 + 1 * 6.941 + 1 * 196.966569 + 1 * 107.8682 + 1 * 195.084 =
239541.2874 g/mol


Mass percent compositionAtomic percent composition

Formula in Hill system is C4HAgArAuBCaClFFeGaHeILiMoN2NaNeO2PtRbSU1001

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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