#### Molar Mass, Molecular Weight and Elemental Composition Calculator

Notice: your compound might have oxygen 'O' misspelled as a zero '0'
Molar mass of Na2S2O3H20 is 178.2665 g/mol
Formula in Hill system is H20Na2O3S2

Elemental composition of Na2S2O3H20:
SymbolElementAtomic weightAtomsMass percent
NaSodium22.98976928225.7926 %
SSulfur32.065235.9742 %
OOxygen15.9994326.9250 %
HHydrogen1.007942011.3082 %

### Computing molar mass (molar weight)

To calculate molar mass of a chemical compound enter its formula and click 'Calculate!'. In chemical formula you may use:
• Any chemical element
• 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.

### 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.