Science Class 8 - Chemical Effects-Of-Electric-Current Notes

Chemical Effects of Electric Current

Welcome to the chapter on Chemical Effects of Electric Current for Class 8. In this chapter, you will learn how electric current can cause chemical changes, what happens when electricity passes through liquids, and how these effects are used in daily life. By the end of this chapter, you will understand the process of electrolysis and its applications!

Introduction

When electric current passes through certain liquids, it can cause chemical changes. This is called the chemical effect of electric current. These changes are important in science and industry.

Conductors and Insulators

• Conductors: Materials that allow electric current to pass through them. Example: metals, salt water.
• Insulators: Materials that do not allow electric current to pass. Example: plastic, pure water.

Electric Current Through Liquids

Some liquids can conduct electricity. These are called electrolytes. When electricity passes through an electrolyte, chemical changes take place.

• Salt water and lemon juice are good conductors.
• Distilled water is a poor conductor.

Chemical Changes Due to Electric Current

• Formation of new substances.
• Release of gases (like hydrogen and oxygen).
• Deposition of metals on electrodes.

Electrolysis

Electrolysis is the process in which electricity is used to break down a liquid (usually water or a solution) into its components.

• Water can be split into hydrogen and oxygen gases by electrolysis.
• Electrolysis is used to purify metals and coat objects with metal (electroplating).

Applications of Chemical Effects

• Electroplating (coating objects with a thin layer of metal).
• Purification of metals.
• Production of chemicals like chlorine and hydrogen.
• Batteries use chemical effects to produce electricity.

Fun Activity: Simple Electrolysis Experiment

Take a glass of salt water, two pencils (as electrodes), and a battery. Connect the pencils to the battery and dip them in the water. You will see bubbles forming—this is a chemical change!

Summary

• Electric current can cause chemical changes in liquids.
• Electrolysis is used to split liquids and purify metals.
• Chemical effects are used in batteries, electroplating, and industry.

Practice Questions

1. What is electrolysis?
2. Name two liquids that conduct electricity.
3. What happens when electric current passes through water?
4. What is electroplating?
5. Why is distilled water a poor conductor?

Challenge Yourself

• Find out how batteries use chemical effects to produce electricity.
• List three uses of electrolysis in daily life or industry.

Did You Know?

• Electroplating is used to make jewelry shiny and prevent rusting!
• The process of splitting water by electricity was discovered in the 1800s.

Glossary

• Electrolysis: Breaking down a liquid using electricity.
• Electroplating: Coating an object with a thin layer of metal using electricity.
• Electrolyte: A liquid that conducts electricity.
• Electrode: A conductor through which electricity enters or leaves a liquid.

Answers to Practice Questions

1. Electrolysis is the process of breaking down a liquid using electricity.
2. Salt water, lemon juice (any two).
3. It splits into hydrogen and oxygen gases.
4. Electroplating is coating an object with a thin layer of metal using electricity.
5. Because it does not have salts or minerals to help conduct electricity.

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Explore the chemical effects of electric current and discover how they are used all around you!