Molar Mass of K2SO3 (Potassium Sulfite)

Molar Mass Calculator

What is the molar mass of K₂SO₃?

Answer

M(K₂SO₃) ≈

158.25 g/mol

Atomic weights: IUPAC standard values (CIAAW, 2024); the sum is rounded to the decimal places of the least precise one — S: 32.06.

Contribution of each element
Element	Atoms, n	Atomic weight, A	n × A, g/mol Mass fraction, w	Mass fraction, w
Kpotassium	2	39.098	78.196 w ≈ 49.41%	≈ 49.41%
Ssulfur	1	32.06	32.06 w ≈ 20.26%	≈ 20.26%
Ooxygen	3	15.999	47.997 w ≈ 30.33%	≈ 30.33%
Σ = 158.253 ≈ 158.25 g/mol w = 100%				100%

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

Mass fractions of the elements

K 49.41%

O 30.33%S 20.26%

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Molar masses of substances nearby

Formula	M, g/mol
KMnO₄ (potassium permanganate)	158.032
Na₂S₂O₃ (sodium thiosulfate)	158.10
(CH₃COO)₂Ca (calcium acetate)	158.166
K₂SO₃ (potassium sulfite)	158.25
CrCl₃ (chromic chloride)	158.35
SrCl₂ (strontium chloride)	158.52
Tb (terbium)	158.93

FAQ

What is the molar mass of K2SO3?

M(K₂SO₃) ≈ 158.25 g/mol

How to calculate the molar mass of K₂SO₃?

Add up the atomic weights of all the atoms in the formula: 2 × 39.098 + 32.06 + 3 × 15.999 = 158.253 ≈ 158.25 g/mol.

How many grams are in 2 moles of K₂SO₃?

m = n × M = 2 mol × 158.25 g/mol = 316.50 g.

See Also