Chemical effect of current-Short answer questions

1.
What do you mean by chemical effect of curent?
ans:
The phenomenon of decomposition of the electrolytes such as NaCl, AgNo3 into their respective ions due to the passage of the electric current is called chemical effect of current.

2.
What is electrolysis?
ans:
The process of decomposition of an electrolyte into its constituent ions by the passage of electric current is called electrolysis.

3.
What is ionization?
ans:
The process of decomposition of the compound into its respective ions is called ionization.

4.
What are electrolytes?
ans:
An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. 

5.
What are electrodes?
ans:
The metal rod or plates which are partially dipped in the electrolyte solution are called electrodes.

6.
Distinguish between conductor and electrolytes.
ans:

Conductor	elecrolyte
Conductor is an object or type of material that allows the flow of electrical current in one or more directions	An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water.
For example, a wire is an electricalconductor that can carry electricity along its length.	For example, NaCl, is placed in water, the salt  dissolves into its component ions, according to the dissociation reaction NaCl(s) → Na+(aq) + Cl−(aq)

7.

What is a voltameter

ans:

Voltammeter is a vessel in which electrolysis is carried out.

8.

Why do electrolytes gets dissosciated when dissolved in liquid?

ans:

Electrolytes dissociates when dissolved in liquid because when  an voltage  is applied to such a solution, the cations of the solution would be drawn to the electrode that has an abundance of electrons, while the anions would be drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution results to a current.

9.

What is the source of emf?

ans:

The source of the emf is the energy provided by the cell or columb of charge passing through it.

10.

State Faraday's Law of electrolytes?

ans:

First law of electrolysis : it state that mass of the substance liberated or deposited at electrode in electrolysis process is proportional to the quantity of electric charge passed through the solution(electrolyte or system).

If m be the mass of the substance deposit at cathode when Q amount of charge is pass on solution.

Then m α Q

Or, m=ZQ where Z is called proportionality constant called electrochemical equivalent of the given substance.

Or, m=ZIt where Q=It

Second law of electrolysis: it state when same amount of electric charge passes through different solution (electrolyte or system) then the mass of the substance deposit or liberated at electrode is directly proportional to their chemical equivalents.

If m1, m2, m3, m4, m5 be the masses liberated in different voltmeter  when same current is passes through them and  E1, E2, E3, E4, E5 be chemical  equivalent respectively. Then we have

m1E1=m2E2=m3E3=m4E4=m5E5   or, mE=aconstant

11.

What is electro chemical equivalent of substance?

ans:

Electrochemical equivalent of the substance is defined as a mass of the substance deposited or liberated on a electrode when one coulomb charge flows through its electrolyte.

12.

What is a chemical equivalent of a substance/

ans:

Chemical equivalent of a substance is defined as the ratio of its mass to its valence

i.e = MV

13.

What is Faraday's constant?

ans:

Faraday’s constant is defined as the amount of charge requires depositing or liberating one mole of monovalent substance during electrolysis. The approximation value of the faraday’s constant is equal to 96500C/mole.

It is given by F= (EQ)/m

Where F= faraday’s constant

E=chemical equivalent of the substance

Q=charge and m=mass of deposit or liberate.

14.

Define 1 faraday.

ans:

1 faraday is defined as the quantity of charge flowing through an electrolyte that will liberate 1 gram-equivalent of any substance at each electrode.

15.

What is electric cell.

ans:

An electric cell is a device that is used to produce the electricity through the chemical reaction

16.

What are the difference between primary and secondary cells?

ans:

Primary cell.	Secondary cell.
(i) Chemical reaction is irreversible.	Chemical reactions are reversible.
(ii) These cells cannot be recharged	These cells can be recharged.
(iii) These cells have high internal resistance.	These cells have low internal resistance.
(iv) High current are not obtained	High current can be obtained.

17.

What are defects of voltaic cells?

ans:

The defects of the simple voltaic cell are

i. local action:

It is due to the presence of the impurities like iron and lead particles on the surface of the zinc these impurities form the tiny voltaic cells in which small electric current are set up. This effect cause the zinc plate to dissolve even when the external current is not send by the cell.

18.

Why is secondary cell called as an accumulator?

ans:

Secondary cell is called an accumulator because it stores the electrical energy in the form of chemical energy and when the outside circuit is closed the current is drawn from the cell by converting the chemical energy into electrical energy..

19.

What do you mean by capacity of a cell?

ans:

Capacity of the cell is defined as the ratio of ampere per hour discharge to the ampere per hour charge or the ratio of the energy given at the discharge to the energy given at the charge.

20.

What do you mean by charging and discharging of a cell/

ans:

The cell is said to be charge if it is connected to the opposition to the supply of the greater emf and the cell is said to be discharged if its terminals are connected to the external resistance.

21.

What is the function of porous pot in primary cell?

ans:

The function of the porous pot is to separate the solution and to complete the circuit by allowing the ions to pass through it.

22.

What are the defects of simple voltaic cell?

ans:

The defects of the simple voltaic cell are

i. local action:

It is due to the presence of the impurities like iron and lead particles on the surface of the zinc these impurities form the tiny voltaic cells in which small electric current are set up. This effect cause the zinc plate to dissolve even when the external current is not send by the cell.

To solve this problem the surface of the zinc is rubbed by the mercury and the mercury layers covers the impurities. However the zinc forms the mercury amalgam combining with it .so, only the zinc is exposed to the acid. Thus th local action doesn’t occur mercury coated with zinc.

ii. Polarisation

the hydrogen which formed by the action of the zinc on the sulphuric acid forms the layer of a

gas on the surface of the copper sulpahte . this weakens action of the cell by increasing the internal resistance of the cell and hindering the deposition of the hydrogen ions on the copper plate   due to which the field is set up and the emf sends the current in opposite direction and weakens the action of cell. To solve this problem the copper plate is taken out anfd  clean with the help of brush

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