Electroplating

WEEK 2 - ELECTROPLATING

DEFINITION OF ELECTROPLATING

Electroplating is the process of depositing a thin layer of one metal onto the surface of another metal object using electric current and an electrolyte solution. It is a type of electrolysis used mainly for coating, protection, decoration, or improving conductivity of objects.

BASIC PRINCIPLE OF ELECTROPLATING

1. Based on electrolysis, where direct current (DC) passes through an electrolyte solution containing metal ions.

2. The metal to be deposited is connected as the anode, and the object to be coated is the cathode.

3. When electricity flows, positive metal ions from the electrolyte are reduced at the cathode and form a coating.

4.Meanwhile, anode dissolves to replenish metal ions in solution (if it's made of the plating metal).

COMPONENTS OF AN ELECTROPLATING

SYSTEM

ELECTROCHEMICAL REACTIONS IN ELECTROPLATING

Example: Electroplating a spoon with copper

* Electrolyte: Copper(II) sulfate solution (CuSO₄)

* Anode: Copper plate

* Cathode: Iron or steel spoon

At Cathode (-):

Cu

2++2e−→Cu(s)

Copper ions are reduced and deposited as metallic copper on the spoon.

At Anode (+):

Cu(s)→Cu

2++2e−

Copper from the anode dissolves to replace ions in the solution.

The thickness of the deposited metal depends on current, time, concentration, and

temperature.

GENERAL CONDITIONS FOR EFFECTIVE ELECTROPLATING

1. Clean surface of the object to be plated

1.  Constant DC current supply

2. Correct concentration of electrolyte

3. Adequate temperature (moderately warm is ideal)

4.  Proper electrode placement

5. Duration long enough for desired thickness

COMMON METALS USED FOR ELECTROPLATING

APPLICATIONS OF ELECTROPLATING
1. Jewelry coating with gold or silver
2. Automobile parts (bumpers, handles)
3. Cutlery and kitchen ware

4. Electrical connectors and circuit boards
5. Coin sand medals
6. Protective coating on tools and machines
7. Galvanization(zinc-plating of iron to prevent rust)

ADVANTAGES OF ELECTROPLATING
1. Enhances appearance (shiny,decorative)
2. Prevents corrosion and rust
3. Improves electrical conductivity
4. Increases surface hardness and durability
5. Reduces friction in machinery parts
6. Makes cheaper metals appear valuable           (e.g., gold-plated items)

DISADVANTAGES/LIMITATIONS OF ELECTROPLATING
1. Costly if precious metals (e.g.,gold, silver) are used.
2. Toxic chemicals used can harm environment if not properly managed
3. Coated layer may wear off over time
4.Requires controlled conditions for quality results
5. Improper cleaning of surfaces leads to poor adhesion

SAFETY PRECAUTIONS IN ELECTROPLATING

1. Use gloves and goggles to handle chemicals.

2. Work in a well-ventilated area.

3. Avoid direct skin contact with electrolyte.

4. Do not allow electrodes to touch inside the beaker.

5. Wash hands and materials after the experiment.

6. Store chemicals safely and label properly.

7. Dispose of used solutions responsibly (do not pour into drains).

EVALUATION

Objective Questions (WAEC/NECO Style):

1. In electroplating, the object to be plated is connected to the:

A. Positive terminal

B. Negative terminal ✅

C. Earth

D. Neutral wire

2. Electroplating involves:

A. Magnetic induction

B. Chemical bonding

C. Electrolysis ✅

D. Radiation transfer

Theory Questions:

1. Define electroplating and explain its working principle.

2. Draw and label a simple electroplating setup.

3. State four uses of electroplating in the industry.

4. What are the reactions at the anode and cathode during copper electroplating?

5. List three factors that influence the quality of electroplating.

6. State two advantages and two disadvantages of electroplating.