Class 8 Science Chemical Effects of Electric Current
If you are looking for Class 8 Science Chemical Effects of Electric Current extra question answers , then you are at the right place.
Q: What makes water a good conductor of electricity?
A: The presence of dissolved salts and minerals makes water a good conductor. Distilled water, which is free of salts, is a poor conductor of electricity.
Q: Why is it dangerous to touch electrical appliances with wet hands?
A: Water containing dissolved salts is a good conductor of electricity, so wet hands can complete an electrical circuit and cause electric shock.
Q: What is an electrode?
A: An electrode is a rod or plate used to conduct electricity into or out of a solution during electrolysis, typically connected to the terminals of a battery.
Q: What are the chemical effects of electric current?
A: The chemical effects include:
Formation of gas bubbles
Deposits of metal on electrodes
Changes in solution color
Chemical reactions in the conducting solution
Q: What is electroplating?
A: Electroplating is the process of depositing a thin layer of one metal onto another material using electricity, typically to improve appearance or protect the underlying metal.
Q: Who discovered the chemical effects of electric current in water?
A: William Nicholson, a British chemist, demonstrated in 1800 that passing current through water produces oxygen and hydrogen bubbles.
Q: How can you test if a liquid conducts electricity?
A: You can use a tester with a bulb or LED, or use a magnetic compass to check for current flow when the tester’s ends are dipped into the liquid.
Q: What happens when salt is added to distilled water?
A: Adding salt to distilled water makes it a good conductor of electricity, as the dissolved salt provides ions that can carry electric current.
Q: What are some common applications of electroplating?
A: Electroplating is used for:
Coating bicycle parts with chromium
Creating gold or silver-looking jewelry
Protecting iron from corrosion by coating with zinc
Making tin-coated food cans
Q: Why do scientists prefer to classify materials as good or poor conductors instead of conductors and insulators?
A: Most materials can conduct electricity under certain conditions, so a more nuanced classification is more accurate.
Q: What types of solutions typically conduct electricity?
A: Solutions of acids, bases, and salts are good conductors of electricity.
Q: How does electroplating protect iron from corrosion?
A: By coating iron with a less reactive metal like zinc, the underlying iron is protected from direct exposure to air and moisture that cause rusting.
Q: What happens to the electrodes during electroplating?
A: One electrode loses metal (dissolves into the solution), while the other electrode gains a coating of metal from the solution.
Q: Why are LEDs useful in electrical testing?
A: LEDs can glow even with weak electric currents, making them more sensitive than traditional bulbs for detecting electrical conductivity.
Q: How do the bubbles form during electrolysis of water?
A: Hydrogen bubbles form at the negative electrode, while oxygen bubbles form at the positive electrode.
Q: Why is chromium used in electroplating?
A: Chromium provides a shiny appearance, resists corrosion, and protects against scratches, while being more economical than making entire objects from chromium.
Q: What happens if you pass current through copper sulphate solution?
A: Copper gets deposited on the electrode connected to the negative terminal of the battery.
Q: Why is it important to clean electrodes before electroplating?
A: Cleaning ensures a better, more uniform metal coating and removes any impurities that might interfere with the process.
