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Q9. When current flows through a conducting solution, chemical reactions are caused. As a result, gas bubbles are formed on the electrodes.
Aim: To decompose water into hydrogen and oxygen
Procedure: 1)Take out two carbon rods from discarded cells and clean them with sandpaper. 2)Make carbon rods as electrodes by connecting them to a battery after wrapping copper wire around them. 3)Take a full cup of water in glass bowl or plastic bowl. 4)Add few drops of lemon juice or a teaspoon of salt to the water. This will make it more conducting. 5)Immerse the carbon rods into the water such that the metal caps of rod are outside the water. 6)Wait for few minutes.
You will observe gas bubbles near the electrodes. The hydrogen is formed on the negative electrode and Oxygen is formed on the positive electrode.
Q10. The shining coating is done on the metal by electroplating. When these are accidently scratched then, the metal will be rusted due to presence of air. So, by some metal these are coated so as to avoid rusting of iron mainly used to build the handlebars and wheel rims.
Q11. In the process of electroplating, the metal to be electroplated is taken as cathode and the one used for coating is chosen as the anode. And, we know, anode is positive terminal and the cathode is negative terminal. Thus, negative terminal will be connected to the iron object.
Q12. The key difference between electrolytes and nonelectrolytes is that electrolytes can produce ions when they are dissolved in water, while nonelectrolytes can’t produce ions.
Q13. When we speak about the cathode in chemistry, it can be said to be the electrode where the reduction takes place. In an electrochemical cell, this is common. Here, the cathode results negative due to the electrical energy that is supplied to the cell results in the decomposition of chemical compounds. However, it can also be said to be positive similar to the case of a galvanic cell where the chemical reaction tends to the generation of electrical energy.
Also, a cathode is said to be either a cold cathode or a hot cathode. A cathode that is heated in the presence of a filament to emit electrons using thermionic emission is called a hot cathode, whereas the cold cathodes are not heated with any filament. In general, a cathode is flagged as "cold" if it emits more electrons than the ones generated by thermionic emission alone.
In the most basic form, an anode in electrochemistry is defined as the point where an oxidation reaction takes place. In general, at an anode, anions, or negative ions, due to its electrical potential, tend to react and give off the electrons. Then, these electrons move up and into the driving circuit.
If we consider a galvanic cell, the anode exhibits a negative in nature, and mostly the electrons move towards the external part of the circuit. Whereas, in an electrolytic cell, it is again given as positive. In addition, an anode can be a wire or a plate having an excess positive charge.
Q14. Chromium is used for electroplating due to its characteristics. It is shiny which makes the object attractive after electroplating. It is corrosion and scratch resistant. Thus, it protects the object from corrosion and scratch.
Q15. All liquid doesn't conduct electricity eg: water is a liquid and it doesn't conduct electricity. Yes to conduct electricity solution must release free ions or charged electrons or their respective atoms to conduct electricity. when we mix ionic compounds to water reaction takes place and this ionic solution releases its ions or electrons to conduct electricity.
Q16. Lemon juice, vinegar and tap water are conductors of heat and electricity. Lemon juice and vinegar contains acids and these acids conducts electricity. Tap water is distilled. Distilled water is a conductor. So, tap water also is a conductor.