(Estimation of Fe2+ in Mohr’s salt using permanganomerty)
The reaction between Mohr’s salt solution and potassium permanganate solution in acid medium is oxidation–reduction or redox reaction where potassium permanganate solution is the oxidizing agent and Mohr’s salt solution is the reducing agent.
MnO4-+ 8H+ + 5e = Mn+2 + 4H2O
5Fe+2 = 5Fe+3 + 5eMnO4-
+ 5Fe+2 + 8H+ = 5Fe+3 + Mn+2 + 4H2O
A. Preparation of 100ml (N\10) standard oxalic acid solution.
Equivalent weight of oxalic acid =63 1000ml of 1(N) oxalic acid solution contain 63gm oxalic acid.
Hence 100 ml (N/10) oxalic acid contain 0.63 gm oxalic acid. About 0.63gm of oxalic acid is weighed from a weighing bottle by difference and is poured into 100ml volumetric flask, dissolved in small volume of water by shaking and
the volume is made up to the mark with distilled water and thoroughly shaken. Therefore, Strength = x/0.63 (N\10) = S1 (N).
B. Standardization of given permanganate solution against standard oxalic acid solution.
The reaction between KMnO4 and oxalic acid is an example of redox reaction. Here acidified KMnO4 acts as an oxidizing reagent while oxalic acid is a reducing agent.