Answer: 53 g/eq
An equivalent weight of a solution is defined as the molecular weight of the solute divided by the valence of the solute. Equivalent weight is used for predicting the mass of a substance that reacts with one atom of hydrogen in an acid-base analysis like in titration.
The salt Na2CO3 ionizes to produce 2Na+ and CO3-2. So the charge on both ions is 2.
Since sodium carbonate contains two atoms sodium, one atom of carbon and three atoms of oxygen. The molecular weight would be
Na : 2 x 23.0 = 46
C : 1 x 12.0 = 12
O : 3 x 16 = 48
When we add up the total values i.e, 46 + 12 + 48 = 106
Therefore, the molar mass of Na2CO3 is 106 g/mole.
Equivalent weight of Na2CO3 = 106 / 2 = 53 g/eq