Molar Mass of Na2S2O3 (Sodium Thiosulfate)

Molar Mass Calculator

What is the molar mass of Na₂S₂O₃?

Answer

M(Na₂S₂O₃) ≈

158.10 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
Nasodium	2	22.990	45.980 w ≈ 29.08%	≈ 29.08%
Ssulfur	2	32.06	64.12 w ≈ 40.56%	≈ 40.56%
Ooxygen	3	15.999	47.997 w ≈ 30.36%	≈ 30.36%
Σ = 158.097 ≈ 158.10 g/mol w = 100%				100%

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

Mass fractions of the elements

S 40.56%

O 30.36%Na 29.08%

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Molar masses of substances nearby

Formula	M, g/mol
C₆H₅Br (bromobenzene)	157.010
Gd (gadolinium)	157.25
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

FAQ

What is the molar mass of Na2S2O3?

M(Na₂S₂O₃) ≈ 158.10 g/mol

How to calculate the molar mass of Na₂S₂O₃?

Add up the atomic weights of all the atoms in the formula: 2 × 22.990 + 2 × 32.06 + 3 × 15.999 = 158.097 ≈ 158.10 g/mol.

How many grams are in 2 moles of Na₂S₂O₃?

m = n × M = 2 mol × 158.10 g/mol = 316.20 g.

See Also