Make a sketch of an electrolytic cell that electroplates nickel onto other metal surfaces. Label the anode and the cathode and indicate the reactions that occur at each.

Understanding the role of the anode and cathode in electrolysis is crucial for comprehending various electrochemical processes, such as electroplating. In an electrolytic cell, the cathode is the electrode where reduction occurs, meaning it gains electrons. In the context of nickel electroplating, the cathode is the metal surface that will be coated with nickel. On the other hand, the anode is where oxidation takes place, which involves losing electrons. For nickel plating, nickel dissolves at the anode to supply nickel ions to the electrolyte.

The functions of the anode and cathode are facilitated by the direct current (DC) power supply, which pushes electrons towards the cathode and pulls them from the anode, thus maintaining the flow of current through the circuit. It is important for students to remember that in electrolytic cells, the anode is positively charged, whereas, in galvanic cells (batteries), the anode is negative. This detail is often a source of confusion, but remembering that electrolytic cells require an external power source can help to distinguish the two processes.

Nickel electroplating involves transferring nickel from the anode to the cathode to create a thin layer of nickel on the surface of another metal. This is achieved through two half-reactions that occur at the respective electrodes. At the anode, the reaction is known as oxidation and is represented by the equation:
\[ \text{Ni} \rightarrow \text{Ni}^{2+} + 2e^- \].
During this reaction, nickel atoms lose electrons and form nickel ions, which then dissolve into the electrolyte solution.

At the cathode, the reaction is termed reduction and can be written as:
\[ \text{Ni}^{2+} + 2e^- \rightarrow \text{Ni} \].
Here, nickel ions from the electrolyte gain electrons and are deposited as a solid nickel layer onto the metal surface serving as the cathode. Students should visualize the reactions occurring simultaneously as the electric current flows through the cell, ensuring the continuous deposition of nickel on the cathode.

The electrolyte solution is a pivotal component in the electroplating process because it allows the movement of ions between the anode and the cathode. For nickel plating, a common electrolyte is a nickel(II) sulfate solution, which contains the nickel ions needed for the deposition at the cathode. The electrolyte must conduct electricity, thereby facilitating the flow of electric current and carrying nickel ions released at the anode towards the cathode.

Furthermore, other substances like boric acid may be added to the solution to refine the plating process, altering the pH, and improving the quality of the nickel deposit. The concentration, temperature, and pH of the electrolyte can all influence the efficiency and outcome of the plating, and it's crucial for students to grasp that these parameters need to be controlled precisely to ensure a smooth, uniform nickel coating.