Question

Determine the molarity of the given KMnO4 solution with the help of supplied M/20Mohr's salt solution

Answer 1

Explanation:

The titration of potassium permanganate (KMnO4) against Mohr salt is an example of redox titration. In close proximity to the endpoint, the action of the indicator is analogous to the other types of visual colour titrations in oxidation-reduction (redox) titrations.

Aim:

To determine the strength of a given potassium permanganate solution against standard ferrous ammonium sulfate (Mohr’s salt) solution.

Theory:

Potassium permanganate is a strong oxidant in the presence of sulfuric acid. Mohr salt is a double salt forming a single crystalline structure having the formula (NH4</sub2SO4. FeSO4. 6H2O. The chemical name for Mohr’s salt is ferrous ammonium sulfate.

In this titration Mohr salt acts as a reducing agent and potassium permanganate acts as an oxidising agent. So, the reaction between Mohr’s salt and potassium permanganate is a redox reaction. In this redox reaction, ferrous ion from Mohr’s salt gets oxidised and pink coloured of manganese present in potassium permanganate, which is in the +7 oxidation state gets reduced to colourless Mn2+ state.

The chemical reaction and the molecular chemical equation is given below.

Reduction half reaction –

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

Oxidation half reaction –

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

Overall reaction –

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

The ionic equation involved in the process is given below.

Oxidation half reaction – [Fe2+ → Fe3+ – e–] x 5

Reduction half reaction – MnO4– + 8H+ + 5e– → Mn2+ + 4H2O

Overall ionic equation – MnO4– + 8H+ + 5Fe2+ → Mn2+ + 5Fe3+ + 4H2O

This titration is based upon oxidation-reduction titrations. When ferrous ammonium sulfate solution is titrated against potassium permanganate in the presence of acidic medium by sulfuric acid. Acidic medium is necessary in order to prevent precipitation of manganese oxide. Here KMnO4 acts as a self indicator and this titration is called permanganate titration.

Materials Required:

Mohr’s salt (ferrous ammonium sulfate)

Potassium permanganate solution

Dilute sulfuric acid

Chemical balance

Burette

Burette stand

Pipette

Conical flask

Funnel

Measuring flask

Weighing bottle

White tile

Burnet

Wire gauze

Answer 2

Answer:

Given = molarity of KMnO4 here, M = molarity V = volume N = number of moles.

To find = solution with the help of supplied M/20Mohr's salt solution

solution =

volume of mohar salt = 20 M

(M₁V₁) N₁= (M₂V₂)N₂

M₁= 0.1 V₁=10Ml

N₁= 20 M₂=?

V₂= 19ml

N₂= 2

put this value in above formula ,

0.1 x 20 x 20 = M₂ x 19 x 2

M₂= 1.05M

molarity of given solution is 1.05M.