Redox titration using sodium thiosulphate as a reducing agent is also known as iodometric titration. The reaction is:- I2(aq) + 2NA2S2O3(aq) 2Nal(aq) + 2Na2S4O6(aq)
I2(aq) + 2S2O32-(aq)2I-(aq) + S4O62-(aq)
In this equation, I2 has been reduced to I-:
2S2O32-(aq)S4O62-(aq) + 2e-
I2(aq) + 2e- 2I-(aq)
The iodine/ thiosulphate titration is a general method for determining the concentration of oxidizing solution. A known volume of an oxidizing agent is added into an excess solution of acidified potassium iodide. The reaction will release iodine:-
a. With KMnO4
2MnO4-(aq) + 16H+ (aq)+ 10I-(aq) 2Mn2+(aq) + 5I2(aq) + 8H2O(I)
b. With KIO3
O3-(aq) + 5I-(aq) + 6H (aq) 3I2(aq) + 3H2O(aq)
The iodine that is released is titrated with a standard thiosulphate solution. From the stoichiometry of the reaction, the amount of iodine can be determined and from this the concentration of the oxidizing agent, which released the iodine, can be calculated....
#6 Determination of Percent Hypochlorite in Clorox by Redox TitrationFall 2004 1
Experiment 6 - Redox Titration
How to prepare a solution of primary standard with a volumetric flask 2.
How to prepare burets for titration3.
How to titrate a sample
Be able to compare and contrast a redox equation (or reaction) and a precipitationequation (or reaction)2.
Be able to write the complete ionic equation for any reaction, especially redox3.
Be able to balance a redox equation4.
Be able to identify the reduction half reaction and the oxidation half reaction5.
Be able to identify the reducing and oxidizing agent in a redox reaction (given the half reactions)6.
Be able to compare and contrast stoichiometric point and endpoint7.
Be able to compare and contrast titrant and analyte8.
Be able to compare and contrast a standardization titration with a...
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