Electrochemistry|9th class|tutoronlines

Chapter No 7


Table of content:

Sr . No Name of element
1 Electrochemistry
2 Oxidation
3 Reduction
4 Spontaneous reaction
5 Non spontaneous reaction
6 Redox reaction
7 Anode
8 Electrochemistry reaction
9 Oxidation number
10 Reducing agent
11 Oxidizing agent
12 Electrolytic cell
13 Strong and Week electrolytic cell
14 Non Electrolytic
15 Galvanic cell
16 Salt Bridge
17 Cathode
18 Nelson cell
19 Electro chemical cell
20 Electrolysis

Give short Answer to the following Questions

Q.No.1. Define oxidation in terms of electrons and give an example?

Ans. Loss of electrons from an atom or ion is called oxidation.

Q.No.2. Define oxidation and reduction?

Ans. During a chemical reaction addition of oxygen and removal of hydrogen is called oxidation while during chemical reaction removal of oxygen and gain of hydrogen is called reduction.

Q.No.3. Define oxidation number with an example?

Ans. The number which represents the charge on an atom or ion is called oxidation number. For example in HCl there is +1 oxidation number of H and -1 for Cl.

Q.No.4. Difference between spontaneous and non spontaneous reaction.
Ans. Spontaneous reaction:

The reaction which can take place by their own without any external agent are called spontaneous reaction.

Non spontaneous reaction:

The reaction which can not take place by their own are called non spontaneous reaction.

Q.No.5. Define redox reaction?

Ans. Those chemical reaction in which oxidation as well reduction reaction has been take place are collectively called redox reaction.

Q.No.6. What type of reaction take place at anode in electrolytic cell?

Ans. In electrolytic cell there is oxidation reaction on anode.

Q.No.7. Define oxidation and reduction in terms of loss and gain of electrons?
Ans. Oxidation:

The removal of electrons from an atom or ion is called oxidation.


Gain of electrons in an atom or ion is called reduction.

Q.No.8. What is spontaneous reaction? In which cell this reaction take place?

Ans. The chemical reaction which takes place in the presence of external agent is known as spontaneous reaction.
These chemical reaction occured in galvanic and electrolytic cell.

Q.No.9. Define electrochemistry. Explain it with a reaction?

Ans. A branch of chemistry tha deal with relationship between electricity and chemical reaction. In this branch redox reaction are studied.

Q.No.10. Define oxidation reaction?

During a chemical reaction gain of oxygen and loss of hydrogen is known as oxidation.

Q.No.11. Calculate oxidation number of nitrogen in HNO3?

Ans. The sum of oxidation number of a compound is zero. According to formula in HNO3. [ Oxidation number of H] + [ oxidation number of N ] + [ oxidation number of O] = 0
By putting values
[ +1 ] + [ oxidation number of N ] +3 [ -2]=0
+1+ oxidation number of N+ [-6]= 0
Oxidation number of N = 6-1=5

Q.No.12. What is the difference between valency and oxidation state?
Ans. Valency:

The combining capacity of an element with other element is called valency.

Oxidation state:

The number which represent the apparent charge on an atom or ion, known as oxidation state.

Q.No.13. Calculate Oxidation number of chlorine in KClO3?

[ oxidation number of K] + [ oxidation number of Cl] + 3[ oxidation number of O] = 0
[+1] + [ oxidation number of Cl] + 3[-2] = 0
+1 + [ oxidation number of Cl] + [-6] =0
Oxidation number of Cl = 6-1 = +5

Q.No.14. Calculate Oxidation number of Sulphur in H2SO4 as ( H= +1, O= -2)?

Ans. 2 [ oxidation number of H] + [ oxidation number of S ] + 4[ oxidation number of O] =0
2[+1] + [ oxidation number of S ] + 4[-2] = 0
2 + [ oxidation number of S ] + [-8] = 0
oxidation number of S = 8-2 = 6

Q.No.15. Calculate the oxidation number of Mn of KMnO4?

Ans. ( oxidation number of K ) + (oxidation number of Mn) + 4 (oxidation number of O) = 0
1+Mn+4(-2) = 0
1+ Mn – 8 =0
Mn = 8-1
Mn = 7

Q.No.16. Define reducing agent also give one example?

Ans. Those species which reduce other substance and themselves get oxidization is know as reducing agent. e.g All metals are good reducing agent.

Q.No.17. Differentiate between oxidizing and reducing agents?
Ans. Oxidizing agent:

The type of specie that oxidize the substance by taking electron form it and themselves get reduced by gaining the electron e.g. non metals are oxidizing agents.

Reducing agent:

The type of specie that reduce other substance by giving them electron and themselves get oxidize. Almost all metal are good reducing agents, because they have tendency to lose electrons.

Q.No.18. Which substance is oxidized and reduced in following reaction. Identify these ?

Ans. In this reaction sodium get oxidize which chlorine become reduce.

Q.No.19. Define electrolytic cell?

Ans. The type of electrochemical cell in which a non spontaneous chemical reaction take place when electric current is passed through solution is called electrolytic cell.

Q.No.20. Differentiate between strong and weak electrolytes?

Ans. Strong electrolytes ionize completely in an aqueous solution. NaCl, NaOH and H2SO4 are example.

Weak electrolytes ionize completely in an aqueous solution CH3COOH and Ca(OH) are examples.


Q.No.21. Explain Non electrolytes with an example?

Ans. Those species that do not ionize in an aqueous solution and current is not passing through their solution is called non electrolytes e.g. sugar solution.

Q.No.22. What is the difference between electrolytic cell and galvanic cell?
Ans. Electrolytic cell:
  1. It consist of complete cell which is connected with battery.
  2. Anode has positive while cathode has negative charge.
  3. Electrical energy is converted into chemical energy.
  4. Current is used for non spontaneous chemical reaction.
Galvanic cell:
  1. It consist of two half cells.
  2. Anode has negative while cathode has positive charge.
  3. Chemical energy is converted into electrical energy.
  4. Redox reaction take place by its own.
Q.No.23. What is salt bridge? What is its basic function?

Ans. The half cells of galvanic are connected by salt bridge. It provide pathway for migration of ions. And keep the solution neutral.

Q.No.24. What is meant by electrolysis?

Ans. When an electric current is passing through a aqueous solution or melted form of a compound it decomposes into its basic component this process is known as electrolysis.

Q.No.25. What is electrochemical cell? Write the name of its types?

Ans. A type of cell in which two electrodes are immersed in electrolyte solution and both are connected with battery.
There are two type of electrochemical cell.
Electrolytic cell, Galvanic cell.

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