Class 9 Chemistry Chapter 7 Question Answer
Important Notes of Class 9 Chemistry Chapter 7 Question Answer English Medium written by Professor M. Shahid Suib. These notes are very helpful in the preparation of Electrochemistry Class 9 for students of the Class 9 Chemistry Chapter 7 Question Answer English Medium and these are according to the paper patterns of all Punjab boards.
Summary and Contents:
Topics which are discussed in the notes are given below:
- Complete Exercise MCQs of Chapter No.7: Electrochemistry
- Complete Exercise Short Questions with Answers of Chapter No.7: Electrochemistry
- Define redox reaction.
- Define oxidation and reduction in terms of electrons. Give an example.
- Differentiate between strong and weak electrolytes. (Also a long question)
- Differentiate between electrolytes and non-electrolytes.
- Differentiate between spontaneous and non-spontaneous reactions.
- What is the difference between valency and Oxidation State?
- Define oxidation and reduction with an example.
- What is galvanizing? Why is galvanizing done?
- Name the metal which is used for galvanizing iron.
- Why is O2 necessary for rusting?
- What is the metallic coating? OR State the best method for the protection of metal from corrosion.
- Define electroplating. Give its uses.
- How is the electroplating of tin on steel carried out?
OR
How electroplating of tin is carried out?
- Define electrochemical cell. Write the names of its types.
- Which type of chemical reaction takes place in an electrolytic cell?
- What is the salt bridge? What is its basic function?
- What is the difference between an anode and a cathode?
- What is corrosion? Give its example.
- Write two methods for the prevention of corrosion.
- How galvanizing of iron sheets is done?
- Define alloy and give an example.
- What is the name of the by-product produced in the Downs cell?
- Name the by-products produced in Nelson’s cell.
- Find out the oxidation number of chlorine in KClO3.
OR
Find out the oxidation number of chlorine in KClO3 as O.N of K = +1 and O.N of O = -2
- Find the oxidation number of nitrogen in HNO3.
- Define oxidation number. Write four rules for assigning oxidation numbers.
- Discuss the electrolysis of water.
- What do you know about the rusting of iron?
- What is the difference between electrolytic and Galvanic cells?
- Electrolytic cells: The type of electrochemical cell in which a non-spontaneous chemical reaction
takes place when electric current is passed through the solution, is called an electrolytic
cell. The process that takes place in an
electrolytic cell is called electrolysis. It is
defined as the chemical decomposition of a
compound into its components by passing
current through the solution of the
compound or in the molten state of the
compound. Examples of these cells are
Downs cell, Nelson's cell.
- Construction of an
Electrolytic Cell: An electrolytic cell consists of a
solution of an electrolyte, two electrodes (anode and cathode) that are dipped in the electrolytic solution and connected to the
battery. The electrode connected to positive terminal is called anode and electrode
connected to the negative terminal is called cathode.
- Working of an Electrolytic Cell: When electric current is applied from battery, the ions in the electrolyte migrate
to their respective electrodes. The anions, which are negatively charged, move towards
the anode and discharge there by losing their electrons. Thus oxidation takes place at
anode. While cations, which are positively charged ions, move towards cathode. Cations
gain electrons from the electrode and as a result reduction takes place at cathode. For
example, when fused salt of sodium chloride is electrolysed the following reactions take
place during this process:
- Galvanic Cell: The electrochemical cell in which a spontaneous
chemical reaction takes place and generates electric current
is called galvanic or voltaic cell. Example of this type of cell
is a Daniel cell.
- Construction of a Daniel Cell: A galvanic cell consists of two cells, each called as
half-cell, connected electrically by a salt bridge. In each of
the half-cell, an electrode is dipped in 1 M solution of its own
salt and connected through a wire to an external circuit.