Question

Design methods using EDTA and redox titration to determine the concentration of C2O4^2- from vegetables . which would ypu prefer, give your reasons

Answer 1

determination of C2O4^2- by redox titration :

this is a carried out by titrating C2O4^2- solution of unknown concentration against MnO4- solution of known concentration in acidic medium.

chemical reaction

2MnO4- + 5C2O4^2- + 16H+ ---> 2Mn2+ + 10CO2 + 8H2O

MnO4- acts as an oxidizing agent and it oxidized C in C2O4^2- to CO2. MnO4- itself gets reduced in the process.

Then EDTA method : here the unknown solution is first reacted with a maetal ion solution of known concentration and known volume which is in excess to complex all of C2O4^2- in solution. The excess left metal ion solution is then titrated with EDTA of known concentration. The amount reacted with EDTA is substrated from the total metal ion solution volume to extimate oxalate in solution. Then called back titration method.

Of the Two, the EDTA method is more reliable and give more precise values as compared to the redox titration methodology.

It is also easy to carry out and we do not have to worry about the end point in the first reaction due to presence of excess metal ion reagent.