3. A 0.7582 g sample of silicate was dissolved and, after a series of operations, transferred to a volumetric flask with a capacity of 500 cm3. In 100 cm3 of the resulting solution, iron was reduced to Fe(II); 6.7 cm3 of potassium dichromate solution with a titer of 0.00049 was used to titrate this solution. Calculate the mass fraction of iron (III) in the sample.

If the file does not open for you, install the Rar archiver program. Inside the archive, the solution is in WORD format.