187. When determining lead in ethyl alcohol, the analyzed solution weighing m (g) was evaporated, the dry residue was dissolved in hydrochloric acid, and the intensity of the luminescence burst when the solution was defrosted (Ix) was measured. Under similar conditions, a burst of luminescence from standard solutions of lead (I) was recorded. A sample of lead weighing 0.1020 g was dissolved in concentrated HCl and the volume of the solution was brought to 100 ml: 1.00 ml of this solution was diluted to 100 ml (solution A). Then the following was added into 100 ml volumetric flasks: 0; 0.1; 0.2; 0.3; 0.4; 0.5 ml of solution A, brought to the mark and obtained the following values of I for standard solutions: 11, 20, 29, 40, 49. Calculate the mass fraction (%) of lead in alcohol if 1 ml of solution was added to the measurement cuvette and obtained the following Ix data:
Problem number 187
m, mg 0.9082
Iх, scale divisions 15

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