16. Solution to Chemistry Problem

702(1). To plot a calibration graph for nephelometric determination of sulfate ion, 25.0 ml of H2SO4 solution containing 0.215 mg/ml SO3 were placed in a 100 ml volumetric flask. Then, BaSO4 suspensions were prepared in 100 ml volumetric flasks containing 20.0 15.0 10.0 6.00 and 2.00 ml of this solution and their apparent optical densities were measured%
VH2SO4 20.0 15.0 10.0 6.0 2.0
Dapp 0.51 0.62 0.80 0.98 1.22
A calibration graph was plotted based on these data. 50.0 ml of the analyzed solution was diluted in a 100 ml volumetric flask. Then 20.0 ml of this solution was transferred to a 100 ml measuring flask, a BaSO4 suspension was prepared in it and brought up to the mark with water. The apparent optical density of this solution was
Option 1
Dapp 0.72
Determine the SO3 content in the analyzed solution (mg/l).