Molar Mass of Fe(OH)2 (Ferrous Hydroxide)

Molar Mass Calculator

What is the molar mass of Fe(OH)₂?

Answer

M(Fe(OH)₂) =

89.859 g/mol

Atomic weights: IUPAC standard values (CIAAW, 2024).

Fe(OH)₂ = Fe + 2 × (O + H) → Fe 1, O 2, H 2

Contribution of each element
Element	Atoms, n	Atomic weight, A	n × A, g/mol Mass fraction, w	Mass fraction, w
Feiron	1	55.845	55.845 w ≈ 62.15%	≈ 62.15%
Ooxygen	2	15.999	31.998 w ≈ 35.61%	≈ 35.61%
Hhydrogen	2	1.0080	2.0160 w ≈ 2.24%	≈ 2.24%
Σ = 89.859 g/mol w = 100%				100%

Atomic weights: CIAAW, Abridged Standard Atomic Weights (2024)

Mass fractions of the elements

Fe 62.15%O 35.61%

H 2.24%

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Molar masses of substances nearby

Formula	M, g/mol
C₅H₁₂O (isoamyl alcohol)	88.150
Y (yttrium)	88.906
C₃H₇NO₂ (L-alanine)	89.094
Fe(OH)₂ (ferrous hydroxide)	89.859
H₂C₂O₄ (oxalic acid)	90.034
HC₃H₅O₃ (DL-lactic acid)	90.078
NaClO₂ (sodium chlorite)	90.44

FAQ

What is the molar mass of Fe(OH)2?

M(Fe(OH)₂) = 89.859 g/mol

How to calculate the molar mass of Fe(OH)₂?

Add up the atomic weights of all the atoms in the formula: 55.845 + 2 × 15.999 + 2 × 1.0080 = 89.859 g/mol.

How many grams are in 2 moles of Fe(OH)₂?

m = n × M = 2 mol × 89.859 g/mol = 179.718 g.

See Also