Gravimetric Analysis Method Analysis

INTRODUCTION
Gravimetric analysis is a quantitative technique of chemical substance by weight. In this analysis, the element to be determined is isolated into a pure form that can be converting into a weighable compound. The technique has the following advantage: It is accurate, less expensive and possible errors can be checked easily through completeness precipitation test. There four different specific gravimetric method that can be used for separation of elements which are: electro method, volatilization method, particulate method and precipitation method. (JEFFERY et al. 1989). The electro-gravimetry method is based on the reduction of metal on a pre-weight electrode and the amount of the analyte is calculated from the weight gained by

After the addition of 32%HCl the sample was filtered under gravity and the filtrate was kept for analysis.
Precipitation

While stirring the solution pH was adjusted to pH~1 using 2M HCl. The solution was heated to almost/ near boiling point (50°c) and an amount of 15ml warm (0.05M) BaCl2 was added drop wisely into the solution with constant stirring. After the addition of warm BaCl2, the precipitation was allowed to settle.
Test for complete precipitation was done by adding few drops of warm BaCl2 to the solution. The solution was allowed to digest for about 40 min in warm water. After the digestion period, the supernatant was tested for complete precipitation by adding few drops of warm BaCl2 until no precipitation was formed.
Filtration step
The solution was filtered using a weighed Millipore filter paper and the precipitate was washed twice with deionised water. The precipitate containing BaSO4 and filter paper were dried and weighed.
Calculations
Mass of BaSO4 (g) = Precipitate + filter paper mass (g) – Tared filter paper mass (g)
Mass of SO4 (g) = Mass of BaSO4 (g) * Molecular weight of SO4 (96.06 g/mol) / Molecular weight of BaSO4 (233.43 g/mol)
SO4 concentration of sample (g/L) = Mass of SO4 (g) / Volume of original sample (25 mL / 1000)