O Level Chemistry – Definitions of Electrolysis

ELECTROLYSIS – This must be one of the most hatred topic on basic Chemistry for many secondary school (local) and high school (regional and western countries) students.

Many find this topic very confusing, especially when application questions are asked in exams. This topic is closely related to REDOX chapter, and yes, if you are confused about REDOX, this is going to be a tough chapter for you. As such, before you try to learn about Electrolysis, do have a good grasp of REDOX first. You can visit our previous blog-posts on Redox by visiting those links shown all the way below.

Let’s start by defining Electrolysis.

Electrolysis is process of using electricity to break down(or decompose) a compound

Takes place in an Electrolytic Cell that has 3 components:
1. Battery
2. Electrodes
3. Electrolyte

Process of Electrolysis involves 3 things:
1. External Circuit
2. Reactions within the Electrolyte
3. Reactions at the surface of the electrodes

When electricity is passed through an electrolyte, chemical reactions take place at the electrodes and electrolyte is decomposed.

Electrolytes can conduct electricity because they contain charged particles (i.e. ions) that are mobile.

Process of gaining or losing electrons at the electrodes is called Discharge. When ions are discharged at the electrodes, they form atoms or molecules.

Redox reactions take place at the electrodes during electrolysis.
@ Cathode, reduction takes place because cations gains electrons
@ Anode, oxidation takes place because anions loses electrons

Let’s check out one exam-based questions to see how much you have learned:

Quick Check 1:
What is the equation for the reaction that takes place at the negative electrode (cathode) during the electrolysis of molten calcium chloride?
A. Ca²⁺ + 2e^– –> Ca
B. Ca –> Ca²⁺ + 2e^–
C. Ca²⁺ + e^– –> Ca⁺
D. 2Cl^– –> Cl₂ + 2e^–

PS: Do try out the question & show yo ur suggested answers in “Comments Section” below

Related Articles:

• O Level Chemistry – Strategies to Predict Products of Electrolysis for Aqueuous Solutions
• O Level Chemistry – Secrets of Redox & Electrolysis Series
• O Level Chemistry – Products of Electrolysis of Molten Compound
• Error in Marshall Cavendish GCE O-Level Chemistry Matters Textbook – Part 1
• O Level Chemistry – Strategies to Predict Products of Electrolysis for Aqueuous Solutions