To estimate the amount of ferrous sulphate dissolved in 750 ml of the given unknown solution volumetrically.

**Estimation of
Ferrous Sulphate (Fe ^{2+}) **

To
estimate the amount of ferrous sulphate dissolved in 750 ml of the given
unknown solution volumetrically. For this you are given with a standard
solution of ferrous ammonium sulphate (FAS) of normality 0.1102 N and potassium
permanganate solution as link solution.

During
these titrations, Fe^{2+} ions (from ferrous salts) are oxidised to MnO_{4}^{-}
ions and MnO_{4}^{-} ion (from Mn^{2+}) is reduced to
Mn^{2+} ion.

**Oxidation** **:** 5
Fe^{2}^{+} →
5 Fe^{3+} + 5e^{−}

**Reduction : **

**Overall reaction:**

5Fe^{2+}
+ MnO_{4}^{-} + 8H → 5Fe^{3+} + Mn^{2+} + 4H_{2}O

**Short procedure :**

(Link
KMnO_{4})Vs (Standard FAS)

Burette
is washed with water, rinsed with KMnO_{4} solution and filled with
same KMnO_{4} solution up to the zero mark. Exactly 20 ml of standard
FAS solution is pipetted out into the clean, washed conical flask. To this FAS
solution, approximately 20ml of 2N sulphuric acid is added. This mixture is
titrated against KMnO_{4} Link solution from the burette. KMnO _{4}
is added drop wise till the appearance of permanent pale pink colour. Burette
reading is noted, and the same procedure is repeated to get concordant values.

(Link
KMnO_{4} )Vs **(**Standard FAS)

Volume of
KMnO_{4} (link) solution (V_{1}) = ----------ml

Normality
KMnO_{4} (link) solution (N_{1}) =-----------N

Volume of
standard FAS solution (V_{2}) = 20 ml

Normality
of standard FAS solution (N_{2}) = 0.1102 N

According
to normality equation: V_{1}× N_{1} = V_{2} × N_{2}

N_{1}
= V_{2} × N_{2} / V_{1}

Normality
of KMnO4 (link) solution (N_{1}) = ----------------- X N

**(**Unknown** **FeSO_{4}** **) Vs
(Link KMnO_{4})

Burette
is washed with water, rinsed with KMnO_{4} solution and filled with same
KMnO_{4} solution up to the zero mark. Exactly 20 ml of unknown FeSO_{4}
solution is pipetted out into the clean, washed conical flask. To this FeSO_{4}
solution approximately 20ml of 2N sulphuric acid is added. This mixture is
titrated against KMnO_{4} Link solution from the burette. KMnO_{4}
is added drop wise till the appearance of permanent pale pink colour. Burette
reading is noted and the same procedure is repeated to get concordant values.

(Link
FeSO_{4} )Vs **(**Unknown FeSO_{4
}solution)

Volume of
Unknown FeSO_{4} solution V_{1
}= 20 ml

Normality
of Unknown FeSO_{4} solution N_{1 }= ? N

Volume of
KMnO_{4} (link) solution V_{2} = ml

Normality
KMnO_{4} (link) solution N_{2}
= X N

According
to normality equation: V_{1}× N_{1} = V_{2} × N_{2 }

N_{1} = V_{2} × N_{2 } / V_{1}

N_{1}=
--------Y--------- N

The
normality of unknown FeSO_{4}
solution = ________________ N

**Weight calculation:**

The
amount of FeSO_{4} dissolved in 1 lit of the solution = (Normality) x
(equivalent weight)

The
amount of FeSO_{4} dissolved in 750 ml of the solution = Normality x equivalentweight x 750 / 1000

The
amount of FeSO_{4} dissolved in 750 ml of the solution = ---g

Tags : Volumetric Analysis | Chemistry Practical Laboratory Experiment Volumetric Analysis | Chemistry Practical Laboratory Experiment

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