Chemistry (Redox)
Experiment 1 : Redox Titration Using Sodium Thiosulphate
Abstract
This experiment is to determine the concentration of oxidizing solution using the iodine/ thiosulphate titration where the reducing solution is potassium iodate solution and the oxidizing solution is sodium thiosulphate solution. Potassium iodate solution which is an oxidizing agent is added into an excess solution of acidified potassium iodide. This reaction will release iodine. Potassium iodide is acidified with sulphuric acid and the iodine released quickly titrated with sodium thiosulphate until it become light yellow. The iodine then detected with starch solution and it turn into dark blue solution and titrated again with sodium thiosulphate until colourless. From the reaction occur, the amount of the iodine can be determined and based on this amount, the concentration of oxidizing agent which released iodine can be determined.
Introduction
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:- Example: 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. Aims a.
Abstract
This experiment is to determine the concentration of oxidizing solution using the iodine/ thiosulphate titration where the reducing solution is potassium iodate solution and the oxidizing solution is sodium thiosulphate solution. Potassium iodate solution which is an oxidizing agent is added into an excess solution of acidified potassium iodide. This reaction will release iodine. Potassium iodide is acidified with sulphuric acid and the iodine released quickly titrated with sodium thiosulphate until it become light yellow. The iodine then detected with starch solution and it turn into dark blue solution and titrated again with sodium thiosulphate until colourless. From the reaction occur, the amount of the iodine can be determined and based on this amount, the concentration of oxidizing agent which released iodine can be determined.
Introduction
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:- Example: 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. Aims a.