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Molar Mass, Molecular Weight and Elemental Composition Calculator

Molar mass of PrSArH2OBrAt2He5Po2Fl20Fr30Rb40Ne is 17082.0215 g/mol

Convert between PrSArH2OBrAt2He5Po2Fl20Fr30Rb40Ne weight and moles
CompoundMolesWeight, g
PrSArH2OBrAt2He5Po2Fl20Fr30Rb40Ne

Elemental composition of PrSArH2OBrAt2He5Po2Fl20Fr30Rb40Ne
ElementSymbolAtomic weightAtomsMass percent
PraseodymiumPr140.9076510.8249
SulfurS32.06510.1877
ArgonAr39.94810.2339
HydrogenH1.0079420.0118
OxygenO15.999410.0937
BromineBr79.90410.4678
AstatineAt209.98714822.4586
HeliumHe4.00260250.1172
PoloniumPo208.98243022.4468
FleroviumFl289.18732033.8587
FranciumFr223.0197363039.1674
RubidiumRb85.46784020.0135
NeonNe20.179710.1181

Computing molar mass step by step

First, compute the number of each atom in PrSArH2OBrAt2He5Po2Fl20Fr30Rb40Ne:
Pr: 1, S: 1, Ar: 1, H: 2, O: 1, Br: 1, At: 2, He: 5, Po: 2, Fl: 20, Fr: 30, Rb: 40, Ne: 1

Then, lookup atomic weights for each element in periodic table:
Pr: 140.90765, S: 32.065, Ar: 39.948, H: 1.00794, O: 15.9994, Br: 79.904, At: 209.987148, He: 4.002602, Po: 208.9824304, Fl: 289.18728, Fr: 223.0197359, Rb: 85.4678, Ne: 20.1797

Now, compute the sum of products of number of atoms to the atomic weight:
Molar mass (PrSArH2OBrAt2He5Po2Fl20Fr30Rb40Ne) = ∑ Counti * Weighti =
Count(Pr) * Weight(Pr) + Count(S) * Weight(S) + Count(Ar) * Weight(Ar) + Count(H) * Weight(H) + Count(O) * Weight(O) + Count(Br) * Weight(Br) + Count(At) * Weight(At) + Count(He) * Weight(He) + Count(Po) * Weight(Po) + Count(Fl) * Weight(Fl) + Count(Fr) * Weight(Fr) + Count(Rb) * Weight(Rb) + Count(Ne) * Weight(Ne) =
1 * 140.90765 + 1 * 32.065 + 1 * 39.948 + 2 * 1.00794 + 1 * 15.9994 + 1 * 79.904 + 2 * 209.987148 + 5 * 4.002602 + 2 * 208.9824304 + 20 * 289.18728 + 30 * 223.0197359 + 40 * 85.4678 + 1 * 20.1797 =
17082.0215 g/mol


Mass percent compositionAtomic percent composition

Formula in Hill system is ArAt2BrFl20Fr30H2He5NeOPo2PrRb40S

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, 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

molecular weights calculated today
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