gramme equivalent cacium carbonate

Gm-Equivalent
is the mass of one equivalent, that is the mass of a given substance which will combine with or displace a fixed quantity of another substance in chemical reaction.

in chemical reaction to have balanced and complete reaction, chemist have to calculate the exact required quantities from each substance or compound to have successful reaction, so they first have to balance the reaction then determine required quantities required from each substance according to this balanced reaction, gram equivalent is the way for this.
gram equivalent is values correspond to the atomic weight of compound divided by the usual valence.
as you see in this example of calcium carbonate compound the atomic weight can be calculated from total sum of atomic weight of all compound atoms; calcium is 40 multiplied by number of calcium atoms plus carbon atom atomic weight 12 multiplied by number of atom 1 plus oxygen atomic weight 16 multiplied by number atoms 3 total is 100 divided by molecule valence which is the combining power between two atoms or atom and molecules, here it is 2 .
so the equivalent number is 100 divided by 2 equals 50.

for example if the chemist determine that a reaction needs 3 gm equivalent of calcium carbonate this means we need 50 gm which is equivalent number of calcium carbonate multiplied by 3 equals 150 gm of calcium carbonate.
also we need to know that 1 m equivalent equals 0.001 gm equivalent
understanding this expression is very mandatory to understand and perform softener design, and we will discuss it more in softener design section