Question

I was electrolysing water with a 12v DC power supply at about 3 milliamps, using copper wire for both my anode and cathode. The solution was about 17 grams of table salt in 750 milliliters of purified water. After running the electrolysis cell for 1 minute, I left it overnight. The next day, I found a light blue powder at the bottom of the cell, which was still full of solution. Could this be copper hydroxide? If not, what could it be?

I should also note that the anode and cathode had become red, similar to what iron oxide looks like.

Answer 1

The blue powder at the bottom of the cell is likely to be copper(II) sulfate, not copper hydroxide. The red color of the electrodes is likely due to the formation of iron oxide.

Step-by-step explanation:

The blue powder at the bottom of the cell is not likely to be copper hydroxide. Copper hydroxide is usually green in color. The blue color could be due to the formation of copper(II) sulfate, CuSO4.

When copper is used as an electrode in an electrolysis cell, it can react with the chloride ions from the salt to form copper chloride. The copper chloride can then react with water to form copper hydroxide. However, in the presence of excess chloride ions, copper chloride can be converted to copper(II) sulfate, which appears as a blue powder.

The red color of the electrodes could be due to the formation of iron oxide. If impurities are present in the copper wire, they can react with the water and oxygen at the anode to form iron oxide, which can give the electrodes a red color.