Science · Class 8
Chemical Effects of Electric Current
Electroplating, electrolysis, and chemical effects in solutions.
4 sections15–25 min read6 MCQs · 2 examples
Chapter Overview
Some liquids conduct electricity through ions. This chapter covers good and poor conductors of electricity, electrolysis, electroplating, and applications.
Conducting Liquids
- Solutions of acids, bases, salts conduct — contain ions
- Distilled water poor conductor; tap water conducts (minerals)
- LED glows in conducting liquid circuit
Electrolysis and Electroplating
- Electrolysis: chemical decomposition by current
- Electroplating: coat metal object with another metal (chromium on taps)
- Cathode: object to plate; anode: plating metal
Applications
- Purification of copper
- Production of chlorine and hydrogen
- Tin coating on food cans prevents rust
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Electroplating
Why are car bumpers chromium plated?
- 1Chromium resists corrosion
- 2Shiny attractive finish
- 3Hard protective layer
Answer
Corrosion resistance and appearance
Conductor test
Will bulb glow in salt solution?
- 1Salt dissolves to Na⁺ and Cl⁻ ions
- 2Ions carry current
- 3Completes circuit — bulb glows
Answer
Yes — ions conduct electricity
Key Points to Remember
- ✓ Liquid conduct due to free ions not electrons mainly
- ✓ Electroplating uses electrolysis
- ✓ Never touch electrical appliances with wet hands
Exam Tips
- • Test liquids with LED tester circuit
- • Explain electroplating of iron with copper
- • Why is distilled water poor conductor?
Practice MCQs — Chemical Effects of Electric Current
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 6Score: 0/0
Tap water conducts because of: