What is the formula mass of anhydrous sodium carbonate? (Given that the atomic masses of sodium, carbon and oxygen are 23 u, 12 u and 16 u respectively)

The formula mass of a compound is the sum of the atomic masses of all atoms in its chemical formula. Anhydrous sodium carbonate has the chemical formula Na2CO3 [1]. To calculate its formula mass, we sum the masses of its constituent atoms: two sodium (Na) atoms, one carbon (C) atom, and three oxygen (O) atoms. Given the atomic masses as Na = 23 u, C = 12 u, and O = 16 u, the calculation is as follows: (2 × 23) + (1 × 12) + (3 × 16). This equals 46 + 12 + 48, resulting in a total formula mass of 106 u [1]. This quantitative approach follows the standard method of determining molar or molecular weight by multiplying the number of moles of each element by its respective atomic weight.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Activity 2.13 > p. 28