21. Решение задачи по химии №002 131

38. A weighed portion of the test sample, which may contain one of the substances: NaOH, Na2CO3, NaHCO3 or one of the mixtures: NaOH Na2CO3, Na2CO3 NaHCO3, was dissolved in water and titrated with an HCl solution with an indicator of phenolphthalein and methyl orange applied sequentially. Determine which substance or mixture of substances is being titrated, and calculate the percentage of the analyte or components in the mixture.
Table 3
Problem No. Substance weight, g HCl concentration Volume of HCl based on phenolphthalein, cm3 Volume of HCl based on methyl orange, cm3
1 2 3 4 5
38 0.2811 0.09132 21.20 21.20

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