Question

In the lab of gravimetric determination of Calcium, how can I use the volume of HCl in this lab to estimate the mass percent of CaCO3?

Answer 1

Gravimetric determination of calcium

Calcium has been gravimetrically determined with sodiumtricupferronatouranylate, which can be directly weighed after drying up to 110 degrees, in the pH range 4.54-7.26. The process happens in presence of magnesium ion.

Regents and chemicals used

• Standard calcium solution

Calcium carbonate was dissolved in dilute hydrochloric acid and calcium content was determined volumetricaly by permanganate method

• Magnesium solution

A weighed amount of magnesium carbonate was dissolved in dilute hydrochloric acid and made up to violume

• Sodiumtricupferronatouranylate

Approximately 2% solution was prepared

Procedure for determination of Calcium

A measured volume of the standard solution of calcium chloride was taken and evaporated to 5 ml. The pH of the solution was adjusted to 4.54-7.26, sodiumtricupferronatouranylate (20-25ml) solution was added with stirring, A light orange solution of the corresponding calcium salt was separated out. It was digested on the water bath for 30 minutes, cooled to room temperature for 2 hour. The precipitate was washed with 0.1% (w/V) reagent solution and once with cold water, dried and weighed. The metal content was calculated on the basis that the precipitated of calciumcupefrranatouranylate. Above 7.26, the precipitated tend to become very fine in nature and difficult to filter. Below 4.54, the precipitate is contaminated with the free tricupferranatouranylicacid