Prove empirically that the ferrous sulfate, the sample of which is given to you, contains an admixture

| September 19, 2021 | education

Prove empirically that the ferrous sulfate, the sample of which is given to you, contains an admixture of ferrous sulfate (111). Write an abbreviated ion-molecular equation.

Iron vitriol is iron (II) sulfate. To detect an impurity of iron (III) sulfate, it is necessary to carry out a qualitative reaction for Fe3 + ions.

There are 2 options for such reactions:

With yellow blood salt (blue precipitate forms):
Fe2 (SO4) 3 + 2K4 [Fe (CN) 6] = 2KFe [Fe (CN) 6] ↓ + 3K2SO4

Abbreviated ionic equation: Fe3 + + K + + [Fe (CN) 6] 4- = KFe [Fe (CN) 6] ↓

With alkali (brown precipitate falls out):
Fe2 (SO4) 3 + 6NaOH = 2Fe (OH) 3 ↓ + 3Na2SO4

Abbreviated ionic equation: Fe3 + + 3OH- = Fe (OH) 3 ↓

In this case, there will also be a reaction with FeSO4, but the precipitate will be gray-green:

FeSO4 + NaOH = Fe (OH) 2 ↓ + Na2SO4



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