Question

to prepare m/20 solution of ferrous ammonium sulphate using this solution find out molarity and strength of the given kmno4

Answer 1

Aim:

Prepare M/20 solution of ferrous ammonium sulphate (Mohr's Salt). Using this solution, find out the molarity and strength of the given KMnO4solution.

Theory:

Molecular mass of Mohr's Salt FeSO4.(NH4)2SO4.6H2O = 392

Therefore to prepare 1000 ml of 1M Mohr's Salt solution, we need 392g of it.

Therefore to prepare 250 ml of M/20 Mohr's Salt solution, we need

392/1000 * 250 * 1/20 = 4.9g

Apparatus required:

Watch glass, beaker, measuring cylinder, pipette, burette, wash bottle, conical flask.

Chemicals required:

Mohr's salt, concentrated H2SO4, M/100 KMnO4solution.

Chemical equations:

Molecular equations-

2KMnO4 + 3H2SO4 -> K2SO4 + 2MnSO4 + 3H2SO4+ 5[O].

[2FeSO4(NH4)2SO4.6H2O + H2SO4 + [O] -> Fe(SO4)3 + 2(NH4)2SO4 + 13H2O]*5

2KMnO4 + 8H2SO4 + 10 FeSO4.6H2O -> K2SO4 + 2MnSO4 + 5Fe2(SO4)3 + 10(NH4)2 + 68H2O

Ionic equations-

MnO4- + 8H+ + 5e- -> Mn2+ + 4H2O

[Fe2+ -> Fe3+ ]*5

MnO4- + 8H+ + 5Fe2+ -> 5Fe3+ + Mn2+ + 4H2O

Indicator:

KMnO4 is a self indicator.

End point:

Colorless to permanent pink color (KMnO4 in the burette).

Observations:

Weight of watch glass = 18g Weight of watch glass + Mohr's Salt = 22.9g Weight of Mohr's Salt = 4.9g

Volume of Mohr's salt solution prepared = 250 ml Molarity of Mohr's salt solution = M/20 Volume of Mohr's salt solution atken for each titration = 10 ml

Calculations:

a) Molarity of KMnO4 solution- From the overall balanced equation, it is clear that 2 moles of KMnO4 react with 10 moles of Mohr's Salt

(MKMnO4 * VKMnO4) / (MMohr's Salt * VMohr's Salt) = 2/10 where M stands for molarity, and V for volume.

Therefore MKMnO4 = 0.01M (Approximately).

b) Strength of the KMnO4 solution. Strength (in g/L) = Molarity * Molar Mass = 0.01 * 158 = 1.58 g/L

Result:

The molarity of the given KMnO4 solution is 0.01M. The strength of the given KMnO4 solution is 1.58g/L.

Answer 2

To prepare m/20 solution of ferrous ammonium sulphate using this solution find out molarity and strength of the given kmno4.This is a redox reacrion.

Explanation:

AIM:-to prepare $M/20$ solution of ferrous ammonium sulphate using this solution find out the molarity and strength of the given $KMnO4$

THEORY:-

Potassium permanganate used in the reaction acts as a strong oxidant in the presence of sulfuric acid.

Mohr's salt is used in the titration which is a double salt. This forms a single crystalline structure.

It has a chemical formula $(NH4)2. FeSO4. 6H2O$

The Chemical formula of mohr's salt is ferrous ammonium sulfate.

Here redox reaction takes place.

The ferrous ion of Mohr’s salt is oxidised and pink coloured of manganese present in potassium permanganate,

Reaction involved :

Reduction reaction :-

$2KMnO4 + 3H2SO4 ---- K2SO4 + 2MnSO4 + 3H2O + 5[O]$

Oxidation reaction :-

$[2FeSO4(NH4)2SO4.6H2O + H2SO4 + [O] --- Fe2(SO4)3 + 2(NH4)2SO4 + 13H2O] x 5$

Overall reaction :-

$2KMnO4 + 10FeSO4(NH4)2SO4.6H2O+ 8H2SO4 --- K2SO4+ 2MnSO4+ 5Fe2(SO4)3+ 10(NH4)2SO4+ 68H2O$

Chemicals required :-

Mohr’s salt (ferrous ammonium sulfate)

Potassium permanganate solution

Dilute sulfuric acid

Glass ware required :-

Chemical balance

Burette

Burette stand

Pipette

Conical flask

Funnel

Measuring flask

Weighing bottle

White tile

Burner

Wire gauze

Procedure:-

Fill the burette with potassium permanganate solution.

Pipette out 25ml of  ferrous ammonium sulphate into a conical flask.

Now add a test tube of sulphuric acid to the solution ferrous ammonium sulphate which helps to prevent oxidation.

Start the titration with potassium permanganate.Mix it well.

At the inital stage purple colour potassium permanganate is discharged with ferrous ammonium solution.

At the end point permanent pink colour reveals the endpoint.

Note the reading at the end point this value is used to find the molarity of the $KMnO4$

Calculations:-

In the reaction the normality is measured with the help of $M1V1 = M2V2$

Strength of the solution$Strength = Normality Equivalent mass$