Tag: electrical cells

Questions Related to electrical cells

Which of the following statement is incorrect about electrochemical cell?

electrical cells patterns and properties of metals chemistry

  1. Electrons are released at anode

  2. Chemical energy is converted into electrical energy

  3. Salt bridge maintains the electrical neutrality of the electrilytes

  4. Cell can work indefinitely

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Correct Option: C

The following electrochemical cell is taken $Cu| Cu^{2+}(aq)|| Ag^{+}(aq))| Ag$ and has emf $E _{r}>0$ by which of the following actions $E _{1}$ increases?

electrical cells patterns and properties of metals chemistry

  1. Adding $NH _{3}$ to the cathodic chamber

  2. Adding $HCl$ to the cathodic chamber

  3. Adding $AgNO _{3}$ to the anodic chamber

  4. Adding $NH _{3}$ to the anodic chamber

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Correct Option: A

Find out ${E} _{cell}$ of following electrochemical cell (${E} _{{Br} _{2}/{Br}^{-}}=1.09V$)
$Pt(s)\mid {Br} _{2}(l)\mid{Br}^{-}(0.01M)\mid\mid{H}^{+}(0.01M)\mid{H} _{2}(g)(1bar)\mid Pt(s)$

electrical cells patterns and properties of metals chemistry

  1. $-1.32V$

  2. $+1.09V$

  3. $-2.15V$

  4. $-1.92V$

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Correct Option: C

The following electrochemical cell has been set up: $Pt(s)|Fe^{3+}, Fe^{2+}(a=1)||Ce^{4+}, Ce^{3+}(a=1)|Pt(s); E^{\circ}(Fe^{3+}|Fe^{2+})= 0.77V$; $E^{\circ}(Ce^{4+}|Ce^{3+})= 1.61V$. If an ammeter is connected between the two platinum electrodes, predict the direction of flow of current. Will the current increase or decrease with time?

electrical cells patterns and properties of metals chemistry

  1. Ce electrode to Fe electrode, decrease

  2. Ce electrode to Fe electrode, increase

  3. Fe electrode to Ce electrode, decrease

  4. Fe electrode to Ce electrode, increase

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Correct Option: A

After some time, the voltage of an electrochemical cell becomes zero. This is because ____________________.

electrical cells patterns and properties of metals chemistry

  1. their electrode potential becomes zero.

  2. their reduction potential become equal but have opposite sign

  3. their reduction potential become equal and have the same sign.

  4. the ions of the electrolyte in the salt bridge stop moving.

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Correct Option: B

Which one of the following statements is incorrect regarding an electrochemical cell?

electrical cells patterns and properties of metals chemistry

  1. The electrode on which oxidation takes place is called anode.

  2. Anode is the negative pole.

  3. The direction of the current is same as that of the direction of flow of electrons.

  4. The flow of current is partly due to flow of electrons and partly due to flow of ions.

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Correct Option: C

The first electro-chemical was invented by:

electrical cells patterns and properties of metals chemistry

  1. Luigi Galvani.

  2. Alessandro Volta.

  3. Deniel.

  4. Lechanche

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Correct Option: A
Explanation:

The first electrochemical cell was invented by Luigi Galvani in 1791. It was greatly improved by Alessandro Volta in the years of 1800.

Statement $1$: In an electrolytic cell, the anode becomes positive and the cathode becomes negative.
Statement $2$: Anions migrate to the anode and cations migrate to the cathode.

electrical cells patterns and properties of metals chemistry

  1. Statement $1$ and Statement $2$ are correct and Statement 2 is the correct explanation of Statement $1$.

  2. Both the Statement $1$ and Statement $2$ are correct, but Statement $2$ is NOT the correct explanation of Statement $1$.

  3. Statement $1$ is correct, but Statement $2$ is not correct.

  4. Statement $1$ is not correct, but Statement $2$ is correct.

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Correct Option: B
Explanation:
|  In electrolytic cell |  In galvanic cell | | --- | --- | |  Anode $=+ve$ |  Anode $=-ve$ | |  Cathode $=-ve$ |  Cathode $=+ve$ |
Anions migrate to anode in electrolytic cell 
Cations migrate to cathode in electrolytic cell 

The apparatus in which electrical energy is converted into chemical energy is known as:

electrical cells patterns and properties of metals chemistry

  1. voltameter

  2. coulometer

  3. both (A) and (B)

  4. none of these

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Correct Option: C
Explanation:

The apparatus in which electrical energy is converted into chemical energy is known as voltameter or coulometer.
Ag or Cu voltameters or coulemeters are used to measure the total charge passed through solution in terms of mass of Ag or Cu deposited there on voltameter or coulometer cathode.

Consider a spontaneous electrochemical cell containing $Cd, Cd^{2+}, Ag^{+}$, and $Ag$.
The reduction potential of $Cd$ is $-0.403\ V$ and $Ag$ is $0.799\ V$.

What is the balanced equation for the reaction that is occurring, and what is the electrochemical cell voltage?

electrical cells patterns and properties of metals chemistry

  1. $Ag^{+} + Cd \rightarrow Cd^{2+} + Ag; 1.19\ V$

  2. $2Ag^{+} + Cd \rightarrow Cd^{2+} + 2Ag; 1.20\ V$

  3. $Ag^{+} + Cd \rightarrow Cd^{2+} + Ag^{+}; 0.40\ V$

  4. $2Ag^{+} + Cd \rightarrow Cd^{2+} + 2Ag; 2,30\ V$

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Correct Option: B
Explanation:
We have,
$E^0$ of Cd = -0.403V ( oxidation will favour)
$E^0$ of  Ag = 0.799V (reduction will favour)

So, the net reaction becomes:

$2 Ag^+ + Cd \rightarrow Cd^{2+} + 2Ag$

and $E^0 _{cell}  = 0.799 - (-0.403) = 1.202 V$