Hydrogen peroxide production in water electrolysis

In summary, the production of hydrogen peroxide during electrolysis will occur at the anode due to the oxidation of oxygen from -II state to -I state. The standard electrode potentials of reactions involving hydrogen peroxide support this, with reaction (3) showing that oxygen can accept electrons from the cathode and combine with hydrogen ions to form hydrogen peroxide. The formation of hydroxide ions from water hydrolysis prevents this reaction from occurring at the cathode, leading to the production of hydrogen peroxide at the anode. This was contrary to the initial assumption that the reaction would occur at the cathode. The formation of bubbles at the anode during electrolysis also supports this conclusion.
  • #1
ComptonFett
8
0
I'm trying to understand my textbook's answer to the following problem:

Q: Electrolysis can under certain circumstances result in the production of hydrogen peroxide. At which electrode will this occur, cathode or anode?

A: During the formation of hydrogen peroxide from water, oxygen is oxidized from -II state to -I state. Oxidation on the other hand takes place at the anode. Therefore hydrogen peroxide is formed at the anode.


The answer did not elaborate any further. I studied the standard electrode potentials of reactions involving hydrogen peroxide and found the following reactions:

\begin{align}
& (1)\quad 2\ H_{2}O\ (l)\to O_{2}(g)+4H^{+}+4e^{-}\quad \left[ -1.23\ V \right] \\
& (2)\quad 2\ H_{2}O\ (l)+2e^{-}\to H_{2}(g)+2\ OH^{-}\quad \left[ -0.83\ V \right] \\
& (3)\quad O_{2}+2\,H^{+}+2\,e^{-}\to H_{2}O_{2}\quad \left[ +0.70\ V \right] \\
\end{align}

Reactions (1) and (2) describe water hydrolysis, I included these just in case someone would find them helpful. Reaction (3) is the one from which I (erroneously) concluded that hydrogen peroxide production would take place at the cathode. I interpreted reaction (3) as showing that oxygen could accept electrons from the cathode and then combine with hydrogen ions to turn into hydrogen peroxide. I reckon that the hydroxide ions from the water hydrolysis could soak up any lingering oxonium ions and this way prevent reaction (3) but I'm not sure if this is the reason why my original reasoning was wrong.

I would appreciate guidance that would show me why my own attempted answer was wrong and what kind of logic I should apply to end up with the correct solution.
 
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  • #2
I think you had the right Idea but just didn't think about it like a real system (as opposed to an equation)

I think 3 is correct but when you place the 2 wires in the water the bubbles form on the anode. When I read your question I thought it was the cathode too until I built one.
 

1. What is hydrogen peroxide production in water electrolysis?

Hydrogen peroxide production in water electrolysis is the process of using an electric current to split water molecules into hydrogen and oxygen gas, with the additional production of hydrogen peroxide as a byproduct.

2. What is the purpose of producing hydrogen peroxide in water electrolysis?

The purpose of producing hydrogen peroxide in water electrolysis is to create a more efficient and sustainable method of obtaining hydrogen peroxide, which is commonly used as a disinfectant, bleaching agent, and chemical intermediate.

3. How is hydrogen peroxide produced in water electrolysis?

Hydrogen peroxide is produced in water electrolysis by using a specialized electrode or catalyst, such as platinum, to facilitate the conversion of oxygen gas into hydrogen peroxide. This process is known as the oxygen reduction reaction (ORR).

4. What are the benefits of producing hydrogen peroxide through water electrolysis?

Producing hydrogen peroxide through water electrolysis offers several benefits, including a more environmentally friendly production method, the ability to produce hydrogen peroxide on-demand, and the potential for cost savings compared to traditional methods of production.

5. Are there any challenges associated with hydrogen peroxide production in water electrolysis?

While hydrogen peroxide production in water electrolysis has many advantages, there are also some challenges to consider, such as the need for specialized equipment and materials, the potential for byproduct contamination, and the optimization of reaction conditions for efficient production.

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