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Molar Mass, Molecular Weight and Elemental Composition Calculator

Molar mass of C21H18N3S2OCl is 427.9701 g/mol

Convert between C21H18N3S2OCl weight and moles
CompoundMolesWeight, g
C21H18N3S2OCl

Elemental composition of C21H18N3S2OCl
ElementSymbolAtomic weightAtomsMass percent
CarbonC12.01072158.9351
HydrogenH1.00794184.2393
NitrogenN14.006739.8185
SulfurS32.065214.9847
OxygenO15.999413.7384
ChlorineCl35.45318.2840

Computing molar mass step by step

First, compute the number of each atom in C21H18N3S2OCl:
C: 21, H: 18, N: 3, S: 2, O: 1, Cl: 1

Then, lookup atomic weights for each element in periodic table:
C: 12.0107, H: 1.00794, N: 14.0067, S: 32.065, O: 15.9994, Cl: 35.453

Now, compute the sum of products of number of atoms to the atomic weight:
Molar mass (C21H18N3S2OCl) = ∑ Counti * Weighti =
Count(C) * Weight(C) + Count(H) * Weight(H) + Count(N) * Weight(N) + Count(S) * Weight(S) + Count(O) * Weight(O) + Count(Cl) * Weight(Cl) =
21 * 12.0107 + 18 * 1.00794 + 3 * 14.0067 + 2 * 32.065 + 1 * 15.9994 + 1 * 35.453 =
427.9701 g/mol


Mass percent compositionAtomic percent composition

Related compounds
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C4H4ClNOSMethylchloroisothiazolinone
C6N5H8SO2ClClothianidin
C6H3Cl4NO2SDavicil
C7H5Cl2NO4SHalazone
C12H16ClNOSBenthiocarb
C5H5Cl3N2OSEtridiazole
C9H4Cl3NO2SFolpet
C7H7Cl2NO2SDichloramine-T
C9H8Cl3NO2SCaptan
C9H12ClNO3SSaclofen

Formula in Hill system is C21H18ClN3OS2

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

molecular weights calculated today
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