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Chapter Analysis
Intermediate12 pages • EnglishQuick Summary
The chapter 'Chemical Effects of Electric Current' explores how electric current causes chemical changes and processes such as electroplating. It covers the concept of good and poor conductors of electricity, specifically focusing on liquids. The chapter also discusses various activities to demonstrate chemical reactions and the industrial use of electroplating for protective and decorative purposes.
Key Topics
- •Conductivity in liquids
- •Chemical effects of electricity
- •Electroplating process
- •Applications of electroplating
- •Identification of positive/negative terminals
- •Current indicators
- •Environmental concerns in electroplating
Learning Objectives
- ✓Understand how electric current causes chemical changes
- ✓Identify good and poor conductors of electricity
- ✓Describe the electroplating process and its applications
- ✓Evaluate the environmental impact of electroplating
- ✓Explain the procedure to test conductivity in liquids
Questions in Chapter
Fill in the blanks. (a) Most liquids that conduct electricity are solutions of _________, _________ and __________. (b) The passage of an electric current through a solution causes _________ effects.
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When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?
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Name three liquids, which when tested in the manner shown in Fig.11.9, may cause the magnetic needle to deflect.
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The bulb does not glow in the setup shown in Fig.11.10. List the possible reasons. Explain your answer.
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A tester is used to check the conduction of electricity through two liquids, labelled A and B. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. You would conclude that (i) liquid A is a better conductor than liquid B. (ii) liquid B is a better conductor than liquid A. (iii) both liquids are equally conducting. (iv) conducting properties of liquid cannot be compared in this manner.
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Does pure water conduct electricity? If not, what can we do to make it conducting?
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In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.
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A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?
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Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Explain.
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Paheli had heard that rainwater is as good as distilled water. So she collected some rainwater in a clean glass tumbler and tested it using a tester. To her surprise she found that the compass needle showed deflection. What could be the reasons?
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Prepare a list of objects around you that are electroplated.
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The process that you saw in Activity 11.7 is used for purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?
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Additional Practice Questions
What is electroplating, and how is it useful in everyday life?
mediumAnswer: Electroplating is the process of depositing a layer of any desired metal on another material by means of electricity. It is useful for preventing corrosion, enhancing appearance, and saving costs by coating expensive metals over cheaper ones.
Describe an activity to test whether lemon juice conducts electricity.
easyAnswer: Take a small amount of lemon juice in a container. Insert the ends of a circuit tester in the juice. If the circuit completes, electricity will flow and the bulb in the tester will glow, indicating that lemon juice is a good conductor of electricity.
What happens when electric current passes through a solution of copper sulphate?
mediumAnswer: When electric current passes through a copper sulphate solution, copper ions move toward the cathode and get deposited there, while an equal amount dissolves from the anode, keeping the solution intact.
Why are LEDs preferred over traditional bulbs for testing weak currents?
easyAnswer: LEDs are preferred because they glow even with small amounts of electric current, unlike traditional bulbs that require a higher current to give off light.
What are the environmental concerns related to electroplating industries?
hardAnswer: Electroplating generates hazardous waste due to the use of chemicals. Disposal of these chemicals, if not managed properly, can lead to environmental pollution.
NCERT Exemplar
AvailablePractice with NCERT Exemplar problems and solutions for this chapter. Exemplar problems are designed to help you master the concepts with advanced-level questions.
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