Electrolysis and Electroplating - Process, Uses, Differences and FAQs

What Is Electrolysis?

The term "electrolysis" was coined by Michael Faraday in the 19th century. In the realm of chemistry, electrolysis is a technique that uses a direct electric current (DC) to drive a non-spontaneous chemical reaction. This process is widely used in industries to separate elements from their natural sources such as ores using an electrolytic cell.

Here's a simple definition of electrolysis:

Electrolysis is the process where ionic substances are broken down into simpler substances when an electric current is passed through them.

The Process of Electrolysis

At its core, electrolysis involves the exchange of ions and atoms through the addition or removal of electrons from the external circuit.

Electrolysis Process

• Ionic compounds are made up of charged particles called ions. For instance, sodium chloride consists of positively charged sodium ions and negatively charged chlorine ions.
• For electrolysis to occur, ions must be free to move. This can be achieved when an ionic substance is dissolved in water or melted. During electrolysis, positively charged ions move towards the negative electrode, and negatively charged ions move towards the positive electrode. The positive ions then gain electrons, while the negative ions lose electrons. The products of this dissociation are collected at the electrodes.
• For example, when electricity is passed through molten sodium chloride, it is broken down into sodium and chlorine, which are collected at their respective electrodes. The metals precipitate, and the gases escape. This ability to break down substances with an electric current has many practical applications.
• Electrolysis is a key process used in electroplating.

Why Is Aluminium No Longer a Precious Metal?

During the medieval times, aluminium was almost as precious as silver due to the difficulty in extracting it. However, with the advent of electrolysis, aluminium transformed from a precious metal to one of the most commonly used metals today. Aluminium is extracted from its ore through the process of electrolytic decomposition and deposition.

What Is Electroplating?

Electroplating is a process that uses an electric current to reduce dissolved metal cations to form a thin coherent metal coating on an electrode.

• Electroplating employs an electric current to reduce dissolved metal ions by electrolysis, resulting in the deposition of metal ions at the other electrode, usually in the form of a uniform coating.
• It involves plating one metal onto another by hydrolysis, primarily for decorative purposes or to prevent metal corrosion.
• There are specific types of electroplating such as copper plating, silver plating, and gold plating. This process allows manufacturers to create products with cost-effective materials and then coat them with metal to add properties such as corrosion resistance, aesthetic appeal, and enhanced strength.

How Does Electroplating Work?

In electroplating, the positive electrode is the metal used for coating the object, and the negative electrode is the object to be coated. The electrolyte is a solution of the coating metal, usually a metal nitrate or sulphate. Let's look at a couple of examples to better understand this process.

Silver Plating:

Silver Plating

In silver plating, the object to be plated is connected to the negative terminal of the power supply, and a piece of silver is connected to the positive terminal. The electrolyte is a silver nitrate solution. This process can also be used to purify silver. An impure silver block is placed at the positive terminal, and a strip of pure silver is attached to the negative terminal. The pure silver is deposited via electrolysis at the negative terminal, leaving the impurities behind.

Copper Plating:

Similar to silver plating, in copper plating, the object to be plated is connected to the negative terminal of the power supply, and a piece of copper is connected to the positive terminal. The electrolyte is a copper sulphate solution.

Copper plating can also be used to purify copper. Both electrodes are made from copper. As the impure positive electrode gradually disappears, leaving the impurities behind, the negative electrode gradually gets coated with pure copper.

Comparing Electrolysis and Electroplating

Here is a comparative table to highlight the differences between electrolysis and electroplating:

Electrolysis	Electroplating
Electrolysis is the process of breaking apart molecules through an electrochemical reaction.	Electroplating involves passing an electric current through a solution containing metal ions, which are then deposited on one of the electrodes.
Electrolysis is useful for carrying out non-spontaneous chemical reactions.	Electroplating is useful when we need to coat one metal with another.
Electrolysis is used to extract metals from their ores.	Electroplating is used to coat pure metals with other metals.
Electrolysis finds applications in electrosynthesis, the mercury cell process, and electrorefining.	Electroplating is used to prevent metals from corrosion.

Electrolysis of Water

The electrolysis of water results in the decomposition of water into oxygen and hydrogen gas. This is accomplished by passing an electric current through the water. Two electrodes are placed in the water, and an electric current is passed through them. The electrodes are usually made of stainless steel or platinum.

The negatively charged electrode, or cathode, is where hydrogen accumulates, while the positively charged electrode, or anode, is where oxygen accumulates. The electrolysis of water is an example of decomposition, also known as electrolytic decomposition.