What is the cathode in electrolysis of aqueous solutions?

The cathode in electrolysis of aqueous solutions is the electrode where reduction occurs.

In the process of electrolysis, an electric current is passed through an aqueous solution (or a molten salt) which causes it to decompose into its elements. This process involves two electrodes: an anode and a cathode. The cathode is the electrode where reduction takes place. Reduction is a chemical reaction where a substance gains electrons.

The cathode is usually marked with a minus (-) sign and is connected to the negative terminal of the power supply. During electrolysis, positive ions in the solution are attracted to the cathode. Here, they gain electrons and are reduced. For example, if you were electrolyzing a solution of copper sulfate, Cu2+ ions would be attracted to the cathode, where they would gain two electrons to become neutral copper atoms. This copper would then be deposited on the surface of the cathode.

It's important to remember that the identity of the cathode can change depending on the specific electrolysis setup. In a rechargeable battery that is being charged, for instance, the cathode would be the electrode where reduction is taking place. However, when the battery is being used and discharging, the cathode becomes the electrode where oxidation occurs.

In summary, the cathode in electrolysis of aqueous solutions is the electrode where reduction happens. It's where positive ions gain electrons and become neutral atoms. The specific reactions that occur at the cathode can vary depending on the solution being electrolyzed and the specific setup of the electrolysis apparatus.