Assay of Calcium Carbonate

Reagent required

Dilute hydrochloric acid
0.05M Disodium Edetate
Sodium hydroxide solution
Calcon mixture

Procedure

Weigh accurately about 0.1 g and dissolve in 3 ml of dilute hydrochloric acid and 10 ml of water. Boil for 10 minutes, cool, dilute to 50 ml with water. Titrate with 0.05M Disodium Edetate to within a few ml of the expected end-point, add 8 ml of sodium hydroxide solution and 0.1 g of calcon mixture as an indicator and continue the titration until the color of the solution changes from pink to a full blue color. Each ml of 0.05M Disodium Edetate is equivalent to 0.005004 g of CaCO3.
Calculation
                    V x M x F          100
% Assay = -------------- x--------------
                    0.05 x W     (100-LOD)
Where,
V = Blank reading – Sample reading
M = Molarity of 0.05M Disodium Edetate
F = Factor
W = Weight of sample