0731. Solving a chemistry problem

46. To construct a calibration curve for the determination of ethanol in kumys, standard alcohol solutions with concentrations of 0.05; 0.1; 0.3; 0.5 and 0.7 g/dm3. Standard solutions were sequentially introduced into the evaporator of a gas chromatograph, and the areas of chromatographic peaks were measured:

Standard solution number 1 2 3 4 5
Peak area, mm2 7.5 15.1 45.0 75.1 105
100 g of kumys was weighed in a distillation flask; after removing CO2, ethanol was distilled into a volumetric flask with a capacity of 50.0 cm3. Chromatography of the distillate was carried out under the same conditions as standard solutions. The peak area was 40.0 mm2. Calculate the mass fraction of ethanol in kumys.