with the help of this solution determine the molarity of given kmno4 solution
Answers
Answer:
To determine the concentration/molarity of KMnO4 solution by titrating it against standard solution of ferrous ammonium sulphate.
(Molar mass of FeSO4(NH4)2SO4 . 6H2O = 392 g mol–1). (i) Weigh 4.9000 g of ferrous ammonium sulphate and transfer it into a 250 mL measuring flask through a funnel.
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.
Calculations:
(a) Normality of KMnO4 solution:
Consider y ml of given KMnO4 solution are equivalent to 20ml of N/10 Mohr’s salt solution.
According to law of equivalents,
N1V1 = N2V2
N1, N2 are normality of Mohr’s salt and KMnO4 solution respectively.
V1, V2 are volume of Mohr’s salt and KMnO4 respectively.
1/10 x 20 = N2 x y
N2 = 2/y
N = Normality of given KMnO4 solution = 2/y
(b) Strength of KMnO4 solution:
Strength = Normality x Equivalent mass
Equivalent mass of KMnO4 =
= 158/5
= 31.6
= 2/y x 31.6 g/liter
Molarity of KMnO4 solution
N = M x Number of electron gained
N = M x 5
M = N/5 moles/ litre
The strength of and molarity of given KMnO4 solution is found out as 2/y x 31.6 g/l and N/5 moles/liter, respectively.
Answer:
with the help of this solution determine the molarity of given KMnO4solutions