Molar Mass of HI (Hydrogen Iodide)

Molar Mass Calculator

What is the molar mass of HI?

Answer

M(HI) ≈

127.91 g/mol

Atomic weights: IUPAC standard values (CIAAW, 2024); the sum is rounded to the decimal places of the least precise one — I: 126.90.

Contribution of each element
Element	Atoms, n	Atomic weight, A	n × A, g/mol Mass fraction, w	Mass fraction, w
Hhydrogen	1	1.0080	1.0080 w ≈ 0.79%	≈ 0.79%
Iiodine	1	126.90	126.90 w ≈ 99.21%	≈ 99.21%
Σ = 127.908 ≈ 127.91 g/mol w = 100%				100%

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

Mass fractions of the elements

I 99.21%

H 0.79%

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Molar masses of substances nearby

Formula	M, g/mol
AgF (silver fluoride)	126.87
I (iodine)	126.90
Te (tellurium)	127.60
HI (hydrogen iodide)	127.91
C₂CaO₄ (calcium oxalate)	128.096
C₁₀H₈ (naphthalene)	128.174
CdO (cadmium oxide)	128.41

FAQ

What is the molar mass of HI?

M(HI) ≈ 127.91 g/mol

How to calculate the molar mass of HI?

Add up the atomic weights of all the atoms in the formula: 1.0080 + 126.90 = 127.908 ≈ 127.91 g/mol.

How many grams are in 2 moles of HI?

m = n × M = 2 mol × 127.91 g/mol = 255.82 g.

See Also