Molar Mass of I (Iodine)

Molar Mass Calculator

What is the molar mass of I?

Answer

M(I) =

126.90 g/mol

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

Elemental iodine is made of I₂ molecules: M(I₂) = 253.80 g/mol = 0.25380 kg/mol.

Contribution of each element
Element	Atoms, n	Atomic weight, A	n × A, g/mol Mass fraction, w	Mass fraction, w
Iiodine	1	126.90	126.90 w = 100.00%	100.00%

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

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Neighbouring elements of the periodic table

Formula	M, g/mol
Sn (tin)	118.71
Sb (antimony)	121.76
Te (tellurium)	127.60
I (iodine)	126.90
Xe (xenon)	131.29
Cs (caesium)	132.91
Ba (barium)	137.33

FAQ

What is the molar mass of I?

M(I) = 126.90 g/mol

Why is the molar mass of iodine 126.90 and not 254?

126.90 g/mol is the mass of one mole of I atoms. Elemental iodine is made of I₂ molecules: M(I₂) = 2 × 126.90 = 253.80 g/mol (254 in school problems); in SI units, 0.25380 kg/mol. In a problem about the gas, the molar mass of iodine is usually M(I₂).

How many grams are in 2 moles of I?

m = n × M = 2 mol × 126.90 g/mol = 253.80 g.

See Also