Titration with potassium iodate: Redox titration
Titration with potassium iodate is a type of redox titration that is used for the determination of reducing agents. The principle of this titration is based on the reaction between potassium iodate (KIO3) and a reducing agent, typically ascorbic acid or iron (II) ions (Fe^2+). In this reaction, the potassium iodate is reduced to potassium iodide (KI) and the reducing agent is oxidized.
The reaction can be represented by the following balanced equation: 5 KIO3 + 3 H2SO4 + 5 KI → 3 I2 + 3 H2O + 5 K2SO4
In this equation, the iodate ion (IO3^-) is reduced to iodine (I2) by the reducing agent, which is then titrated with a standardized solution of sodium thiosulfate (Na2S2O3) to determine its concentration.
The endpoint of the titration is determined by the addition of starch indicator, which forms a blue-black complex with the iodine. As the sodium thiosulfate solution is added, the iodine is reduced back to iodide ions (I^-), and the blue-black color of the starch-iodine complex disappears. At the endpoint, all the iodine has been reduced to iodide ions, and the disappearance of the blue-black color indicates the endpoint of the titration.
Titration with potassium iodate is commonly used in the food industry for the determination of vitamin C content in foods and beverages. Vitamin C, also known as ascorbic acid, is a reducing agent that can reduce potassium iodate to iodine, which can then be titrated with sodium thiosulfate. The concentration of vitamin C can be calculated based on the amount of sodium thiosulfate required to titrate the iodine to the endpoint.
Overall, titration with potassium iodate is a useful analytical technique for the determination of reducing agents, and is commonly used in various industries and research fields.
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