16. Solution to Chemistry Problem

5. To plot the calibration graph for cadmium determination, a standard solution of cadmium salt C(1/2Cd2+)=1*10-4 mol*l-1 was used. Aliquots of this solution Vst (1.0; 2.0; 3.0; 4.0; 5.0; 6.0 ml) were diluted with background in a cell to 25.0 ml and polarographed. The following data were obtained:
Vst, ml 1.0 2.0 3.0 4.0 5.0 6.0
h, mm 9.0 16.0 26.5 35.0 41.0 54.0
A weighed sample m (g) of the alloy containing cadmium was dissolved in nitric acid, the acid was removed by evaporation, and the residue was diluted to a volume of V (ml). An aliquot of 5.0 ml was introduced into the cell and the volume was brought up to 25.0 ml with background. When polarographically measuring under the same conditions as standard solutions, the following data were obtained:
variant m, g V, ml h, mm
5 0.200 50.0 10.8
Calculate the mass fraction w (%) of cadmium in the alloy sample.