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A student was instructed to prepare 19.2 g of pure Na2S2O3·5H2O. The student was provided solid Na2S2O3·5H2O, containing 15 wt. % water-insoluble impurities. According to the procedure for purification of this compound by recrystallization, a saturated (at 40 oC) aqueous solution of sodium thiosulfate is first prepared. The suspension is heated to 50 °С and subsequently filtered hot. The filtrate is then cooled to 0 °C for crystallization. The solubility of Na2S2O3 at 40 С is 102.6 g per 100 g of water, at 0 °С it is 52.5 g per 100 g of water. What mass of contaminated Na2S2O3·5H2O and water (g) should the student use for recrystallization?
Enter the answer rounded to integer values in the format of ... and ..., for example, 10 and 12.