Can this electrochemical reaction be explained? Steel, copper and electricity

In summary, a fourth-grade science experiment was conducted to make a steel nail rust using an electrolyte solution of salt and water. After no noticeable activity, electricity was added using a 12V/500mA wall wart and a piece of copper as the cathode. After 10 minutes, the water turned dark and a brown scum formed on the surface. The reaction was continued for a couple hours and when the nail was retrieved, it appeared to be pickled rather than rusted. The question is what process occurred to the nail, with two possible explanations being an acidic bath from the liberation of hydrogen and loose chlorine atoms, or a thin layer of iron oxide. Further information may be needed about the electrode material to fully understand the reaction
  • #1
MarkSheffield
15
0
My son brought home a fourth-grade science experiment a few days ago: He was to make some sort of property change in a steel nail. He had decided that he wanted to make it rust, so we set about creating an electrolyte solution out of salt and water and leaving it in there. There wasn't noticeable activity there for a few days, so we decided to add some electricity.

I used a 12V/500mA wall wart as the source and a piece of copper as the cathode, a clip onto the nail for the anode, all immersed into a bath of salt (NaCl) water. After 10 minutes, the water had turned completely dark, almost black, with a brown scum floting on the surface.

I was shocked at the rate of the reaction. I ran this for a couple hours, there was quite a bit of current running through it as the wall-wart got very hot. When the nail was retrieved from the bath, it looked like it had been pickeled rather than rusted, as there was only a pitting of the outer surface (total loss of the original surface sheen) but not red/brown at all.

My question is: What is the process that occurred to the nail? I see two choices, maybe there are more:

An acidic bath of HCl from the liberation of hydrogen from the water due to the electrical current, combining with the loose Cl atoms from the salt.

Iron oxide in a very thin layer

Can anyone explain what went on?
 
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  • #2
No idea what have happened - but a lot may depend on the electrode material - read 'what the nail was really made of'.
 

Related to Can this electrochemical reaction be explained? Steel, copper and electricity

1. Can you explain the electrochemical reaction that occurs between steel, copper, and electricity?

Yes, the electrochemical reaction between steel, copper, and electricity can be explained. When electricity is passed through a solution containing steel and copper, a redox reaction occurs. The copper acts as the cathode and gains electrons, while the steel acts as the anode and loses electrons. This creates a flow of electrons through the external circuit, resulting in a transfer of ions between the two metals.

2. How does the type of steel used affect the electrochemical reaction?

The type of steel used can affect the electrochemical reaction in several ways. The composition and purity of the steel can impact its reactivity, as well as its surface area and exposure to oxygen. Different types of steel may also have different potentials for oxidation and reduction, which can influence the overall reaction.

3. What factors can influence the rate of the electrochemical reaction between steel and copper?

The rate of the electrochemical reaction between steel and copper can be influenced by several factors. These include the concentration and temperature of the solution, the surface area and composition of the metals, and the strength and direction of the electric current. Other factors such as impurities in the solution or the presence of catalysts can also play a role.

4. Is the electrochemical reaction between steel and copper reversible?

Yes, the electrochemical reaction between steel and copper is reversible. This means that the reaction can proceed in both the forward and reverse directions, depending on the conditions. For example, if the electric current is reversed, the ions will flow in the opposite direction and the reaction will reverse.

5. Can the electrochemical reaction between steel and copper be used for practical applications?

Yes, the electrochemical reaction between steel and copper has many practical applications. It is commonly used in batteries and fuel cells, as well as in metal plating and corrosion protection. This reaction can also be harnessed for energy storage and conversion, making it an important area of study in the field of renewable energy.

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