15. A portion of copper-containing nickel-zinc ferrite weighing m g was dissolved and 100.0 ml of solution was obtained. An aliquot with a volume of Val ml was placed in a separating funnel, the necessary reagents were added and copper was extracted with three portions of 10.0 ml of ethyl acetate. The combined extract was made up to 50.00 ml with ethyl acetate, photometrically and AX absorbance values were obtained.
Determine the mass fraction (%) of copper in ferrite using the following data obtained under similar extraction and photometry conditions (VCT ml of CuSO4 standard solution, the concentration of copper in which was 2 μg / ml) to build a calibration graph:
m,g 0.982
AX 0.580
VAL, ml 20.0
VCT, ml 20.0
AST 0.500
Answer: 3) 3.9 * 10-2%.

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