Reaction: Ca2+ + H2Y2- -> CaY2- + 2 H+ Chemicals and solutions - Sample solution containing calcium — Physical Chemistry — Kinetics Chemistry Question

Reaction: Ca²⁺ + H₂Y^2- → CaY^2- + 2 H⁺

Chemicals and solutions
- Sample solution containing calcium (prepared from A.R. grade CaCl₂)
- Patton and Reeders indicator
- KOH solution
- EDTA disodium salt

Preparation of EDTA solution (c = 0.01 mol dm^-3)
Weigh 1.861 g of Na₂EDTA (AR grade) and quantitatively transfer it to 500 cm₃ volumetric flask. Add distilled water to the flask to dissolve Na₂EDTA and make up the solution to 500 cm₃ mark with distilled water.

Procedure
Dilute the given sample solution to 100 cm₃ in a 100 cm₃ volumetric flask using distilled water. Pipette out 25 cm₃ of the diluted sample solution in a clean conical flask. Add 25 cm₃ of distilled water and adjust the pH using freshly prepared KOH solution to 12. Check the pH with pH paper. Add a pinch of solid indicator and titrate with Na₂EDTA solution till the colour changes from wine red to blue.