Chapter 14: Chemical effects of electric current

These NCERT Class 8 Science Chapter 14 notes explain the chemical effects of electric current in a clear and structured way. The chapter focuses on how electric current can cause chemical changes in substances.

It discusses conductors and insulators, conducting liquids, electrolysis and the role of electrodes such as anode and cathode. The chapter also explains electroplating and its practical uses in daily life and industry.

Chapter 14 – Chemical Effects of Electric Current is important for understanding basic electrochemistry and real-life applications like metal coating and purification. It is highly relevant for school examinations and foundation level competitive preparation.

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1. Introduction: electricity and chemical change

• Electric current can produce heating, magnetic and chemical effects.
• The chemical effect occurs when electricity causes a chemical change in a substance.
• Passing current through certain liquids leads to visible changes.
• Gas bubbles or metal coating may appear during the process.
• These changes show the chemical effect of electric current.

2. Conductors and insulators of electricity

• Conductors are substances that allow electric current to pass through them.
• Examples of conductors include copper, aluminium and iron.
• Insulators are substances that do not allow electric current to pass.
• Rubber, plastic and wood are common insulators.
• Conductors are used in wires, while insulators provide safety.

3. Conducting liquids

• Some liquids can also conduct electricity and are called conducting liquids.
• Lemon juice, salt solution and vinegar are examples.
• Distilled water does not conduct electricity in pure form.
• Adding salt or acid makes water conducting.
• Kerosene is a non-conducting liquid.

4. Chemical effects of electric current

• When current passes through a conducting liquid, gas bubbles may form.
• The colour of the solution may change.
• Metal may deposit on the electrodes.
• These changes indicate a chemical effect.
• The process involves chemical reactions.

5. Electrodes and their types

• Electrodes are metal rods or plates dipped in a conducting liquid.
• The positive electrode is called the anode.
• The negative electrode is called the cathode.
• Chemical reactions occur at the electrodes.
• Electrodes help complete the electric circuit in liquids.

6. Electrolysis and its example

• Electrolysis is the chemical decomposition of a liquid using electricity.
• It occurs when current passes through a conducting liquid.
• During electrolysis of water, it splits into hydrogen and oxygen.
• This process shows breakdown of compounds.
• Electrolysis is used in many industrial processes.

7. Electroplating and its advantages

• Electroplating is the process of coating one metal with another using electric current.
• It improves appearance and shine of objects.
• Electroplating prevents rusting and corrosion.
• Chromium plating is used on car parts and taps.
• Gold plating is used in jewellery.

8. Applications of chemical effects of electric current

• Electroplating is used to coat metals for protection.
• Electrolysis is used for purification of metals.
• Batteries work on chemical effects of electricity.
• Chemical separation processes use electrolysis.
• Many industrial processes depend on these effects.

9. Useful and harmful effects

• Useful effects include metal coating and purification.
• Chemical separation is also a useful application.
• Harmful effects include corrosion of wires.
• Batteries may get damaged due to chemical reactions.
• Proper handling reduces harmful effects.

10. Tester and its importance

• A tester is used to check whether a substance conducts electricity.
• It consists of a battery, wires and a bulb or LED.
• If the bulb glows, the substance conducts electricity.
• LED glows even with weak current.
• Tester helps in identifying conductors and insulators.

11. Key exam-oriented keywords explained

• Electric current: Flow of electric charge through a conductor.
• Chemical effect: Chemical change produced by electric current.
• Conductors: Substances that allow electric current to pass.
• Insulators: Substances that do not allow electric current to pass.
• Conducting liquids: Liquids that allow current to pass.
• Electrodes: Metal rods or plates used in conducting liquids.
• Anode: Positive electrode in electrolysis.
• Cathode: Negative electrode in electrolysis.
• Electrolysis: Decomposition of a liquid by passing electric current.
• Electroplating: Coating of one metal over another using electricity.
• Tester: Device used to check conductivity of substances.

12. One-page summary for quick revision

• Electric current can produce chemical changes.
• Some liquids conduct electricity and show chemical effects.
• Electrolysis breaks compounds into simpler substances.
• Electroplating protects and beautifies metals.
• Tester helps identify conducting materials.

Understanding NCERT Class 8 Science Chapter 14 is essential to learn how electricity can bring chemical changes. The chapter clearly explains electrolysis, electroplating and the working of a tester.

The concepts help students understand practical applications in industries and daily life. It is highly useful for school exams and foundation competitive preparation.

Continue reading NCERT Class 8 Science Chapter 15 – Some Natural Phenomena to understand lightning and earthquakes.

FAQs

Q1. What is the chemical effect of electric current?
The chemical effect of electric current refers to chemical changes that occur when current passes through a conducting liquid.

Q2. What are electrodes?
Electrodes are metal rods or plates dipped in a conducting liquid to allow current to pass.

Q3. What is electrolysis?
Electrolysis is the process of chemical decomposition of a liquid using electric current.

Q4. What is electroplating?
Electroplating is the process of coating one metal over another using electric current.

Q5. Why is this chapter important for exams?
It explains electrolysis and electroplating concepts, which are important for school exams and foundation preparation.

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