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

Molar mass of As2O5 is 229.8402 g/mol
Convert between As2O5 weight and moles
CompoundMolesWeight, g
As2O5

Elemental composition of As2O5
ElementSymbolAtomic weightAtomsMass percent
ArsenicAs74.92160265.1945
OxygenO15.9994534.8055

Mass percent compositionAtomic percent composition

Sample reactions for As2O5
EquationReaction type
As2O5 + H2O = H3AsO4synthesis
As2O5 + Ca(OH)2 = Ca3(AsO4)2 + H2Odouble replacement
BaO + As2O5 = Ba3(AsO4)2synthesis

Formula in Hill system is As2O5

### 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.

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.

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