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Molar Mass, Molecular Weight and Elemental Composition Calculator

Molar mass of Ethanol (C2H5OH) is 46.0684 g/mol

Convert between C2H5OH weight and moles
CompoundMolesWeight, g
C2H5OH

Elemental composition of C2H5OH
ElementSymbolAtomic weightAtomsMass percent
CarbonC12.0107252.1429
HydrogenH1.00794613.1275
OxygenO15.9994134.7296

Computing molar mass step by step

First, compute the number of each atom in C2H5OH:
C: 2, H: 6, O: 1

Then, lookup atomic weights for each element in periodic table:
C: 12.0107, H: 1.00794, O: 15.9994

Now, compute the sum of products of number of atoms to the atomic weight:
Molar mass (C2H5OH) = ∑ Counti * Weighti =
Count(C) * Weight(C) + Count(H) * Weight(H) + Count(O) * Weight(O) =
2 * 12.0107 + 6 * 1.00794 + 1 * 15.9994 =
46.0684 g/mol


Mass percent compositionAtomic percent composition

Appearance
Ethyl alcohol, also known as ethanol, is a colorless liquid with a characteristic odor.

Sample reactions for C2H5OH
EquationReaction type
C2H5OH + O2 = CO2 + H2Ocombustion
C2H5OH + O2 = CO + H2Oincomplete combustion
C2H5OH + PCl3 = C2H5Cl + H3PO3double replacement
C2H5OH + O = CO2 + H2Odouble replacement
C2H5OH + CH3CO2H = CH3CO2C2H5 + H2Odouble replacement

Formula in Hill system is C2H6O

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, Ts, Tos, Bz, TMS, tBu, Bzl, Bn, Dmg
  • parantesis () or brackets [].
  • Common compound names.
Examples of molar mass computations: NaCl, Ca(OH)2, K4[Fe(CN)6], CuSO4*5H2O, water, nitric acid, potassium permanganate, ethanol, fructose, caffeine.

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 of molecular mass, molecular weight, molar mass and molar weight

  • 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.
Weights of atoms and isotopes are from NIST article.

Related: Molecular weights of amino acids
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