Potassium Iodide as a catalyst for Hydrogen Peroxide

[tongangeline_657]

Hey, I am having trouble understanding the type of reaction that occurs between potassium iodide, and hydrogen peroxide. A website I looked at said that potassium iodide was a catalyst for Hydrogen peroxide, but potassium iodide doesn't work in the same way that a catalyst described by a textbook does, as it gets 'used up' and becomes Iodide, hence it is more like a redox reaction. Could someone please help explain? I am really curious!

 

[Bystander]

Hey, I am having trouble understanding the type of reaction that occurs between potassium iodide, and hydrogen peroxide. A website I looked at said that potassium iodide was a catalyst for Hydrogen peroxide, but potassium iodide doesn't work in the same way that a catalyst described by a textbook does, as it gets 'used up' and becomes Iodide, hence it is more like a redox reaction. Could someone please help explain? I am really curious!

Answering your three two questions in order: inadequate reference; yes, you've understood correctly.

 

[mjc123]

Depends on the pH. In acidic solution, iodide is oxidised to iodine:
2I^- + H₂O₂ + 2H⁺ → I₂ + 2H₂O
In alkaline solution, the same oxidation occurs, but I₂ can also oxidise H₂O₂ to oxygen:
2I^- + H₂O₂ → I₂ + 2OH^-
I₂ + H₂O₂ + 2OH^- → 2I^- + O₂ + 2H₂O
Overall 2H₂O₂ → O₂ + 2H₂O