Tag: electrochemistry

Questions Related to electrochemistry

Metals are good conductors of electricity because of which of the following reasons?

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. Metals have free electrons

  2. Metals have free ions

  3. Metals have free atoms

  4. None of the above

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Correct Option: A
Explanation:

Metal atoms have outer electrons which are not tied to any other atom. Thus metals have free electrons. This electron can move freely in the metal structure. Because of the presence of this free electron metals can conduct electricity. Electricity is the flow of electrons.

In a conduction process,change of mass was observed. The conduction type can be:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. metallic

  2. electrolytic

  3. may be any one of these

  4. none of these

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Correct Option: B
Explanation:

In a conduction process,change of mass was observed. The conduction type can be electrolytic as electrolytic conduction takes place due to flow of ions thus electrolytic conduction involves transfer of matter.

Which of the following sentences about conduction is/are true?

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. Metallic conduction decreases with increase in temperature

  2. Electrolytic conduction increases with increase in temperature

  3. Both of the above

  4. None of the above

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Correct Option: C
Explanation:

Electrolytic conduction occurs because of the flow of ions. As the temperature increases, the degree of ionization of the electrolyte also increases. Hence the flow of ions also increases. So, electrolytic conduction increases with the increase in temperature.
Metallic conduction occurs because of the flow of electrons. As the temperature rises the metal atoms vibrate more. And hence the resistance offered by the moving electrons also increases. Because of this resistance, the conduction decreases. So metallic conduction decreases with increase in temperature.

Which among the following solutions is NOT used in determination of the cell constant?

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. ${ 10 }^{ -2 }MKCl$

  2. ${ 10 }^{ -1 }MKCl$

  3. $1 M KCl$

  4. Saturated $KCl$

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Correct Option: D

Metallic conduction involves:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. no chemical change

  2. flow of electrons

  3. transfer of matter

  4. conductance decreases with increase in temperature

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Correct Option: B,D
Explanation:

The substances which allow the flow of electric current are called conductors. The good metal conductors are copper, silver, tin, etc. 


It is due to the flow of electrons. It is not accompanied by the decomposition of the substance, only physical changes occur. It also does not involve the transfer of matter it is due to the flow of electrons. 

Conductivity decreases with an increase in temperature due to an increase in the number of collisions.

Hence, the correct options are $B$ and $D$

In Death valley,California,a conduction process was going on in an air conditioned room maintained at $30^0$.Suddenly there was a power cut and temperature started to rise and it was found that the conduction process got slower.The conduction type can be:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. electrolytic

  2. metallic

  3. any of these

  4. none of these

Show answer
Correct Option: B
Explanation:

As temperature rises, thermal conductivity of metals decreases due to increase in molecular collisions.

Ionic conductance of ${ H }^{ + }$ and ${ SO } _{ 4 }^{ 2- }$ are $x$ and $yS\ { cm }^{ 2 }\ { mol }^{ -1 }$. Hence, equivalent conductivity of ${ H } _{ 2 }{ SO } _{ 4 }$ is:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. $2x+\cfrac { y }{ 2 } $

  2. $x+\cfrac { y }{ 2 } $

  3. $\cfrac { x }{ 2 } +y$

  4. $\cfrac { x }{ 2 } +\cfrac { y }{ 2 } $

Show answer
Correct Option: A
Explanation:

Equivalent conductance can be defined as the conductance produce by an equivalent of ion present in the solution.

For ${ H }^{ + }$, no.of ${ e }^{ - }$ change $=1$
For ${ SO } _{ 4 }^{ 2- }$, no.of ${ e }^{ - }$ change $=2$
Thus equivalent conductance of ${ H } _{ 2 }{ SO } _{ 4 }$
${ H } _{ 2 }{ SO } _{ 4 }$ $\rightleftharpoons 2{ H }^{ + }+{ SO } _{ 4 }^{ 2- }$
Eg Conductance $=\cfrac { 2[Ionic\quad conductance\quad of\quad { H }^{ + }] }{ nf } +\cfrac { Ionic\quad Conductance\quad of\quad { SO } _{ 4 }^{ 2- } }{ nf } $
Eg. Conductance $=2\times \cfrac { x }{ 1 } s{ cm }^{ 2 }+\cfrac { y }{ 2 } s{ cm }^{ 2 }$
Eg. Conductance $=2x+\cfrac { y }{ 2 }$

In passing $3\ F$ of electricity through three electrolytic cells connected in series containing $Ag^{\oplus}, Ca^{2+}$, and $Al^{3+}$ ions, respectively. The molar ratio in which the three metal ions are liberated at the electrodes is:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. $1 : 2 : 3$

  2. $2 : 3 : 1$

  3. $6 : 3 : 2$

  4. $3 : 4 : 2$

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Correct Option: C
Explanation:

For all the solution $Q=i\times t$ is same,

${ n } _{ Ag }=\cfrac { Q }{ nF } =\cfrac { Q }{ F } ({ Ag }^{ + }+{ e }^{ - }\longrightarrow Ag)$
${ n } _{ Ca }=\cfrac { Q }{ 2F } ({ Ca }^{ 2+ }+2{ e }^{ - }\rightarrow Ca)$
${ n } _{ Al }=\cfrac { Q }{ 3F } ({ Al }^{ 3+ }+3{ e }^{ - }\rightarrow Al)$
$\therefore $ ${ n } _{ Ag }:{ n } _{ Ca }:{ n } _{ Al }=1:\cfrac { 1 }{ 2 } :\cfrac { 1 }{ 3 } =6:3:2$
$\therefore $   Molar ratio$=6:3:2$.

Which of the following statement is incorrect with respect to metallic or electronic conductivity ?

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. Metallic conductivity depends on the number of electrons in the valence shell of an atom of metal

  2. Metallic conductivity depends on the structure of metal and its characteristics

  3. The electrical conductivity of metal increases with increase in temperature

  4. There is no change in the structure of metal during electrical conduction

Show answer
Correct Option: C
Explanation:

Metallic or electronic conductivity is due to the presence of free electrons or/and holes (positive charge). It depends upon:
(i) Number of valence electrons present in the metal 
(ii) Structure and nature (characteristic) of metal 
(iii) Density of metal 
(iv) Temperature 


With increase in temperature, electronic conductivity decreases because the arrangement of electrons gets disturbed. Metallic conductivity does not affect the structure of the metal. 

At infinite dilution equivalent conductances of $B{ a }^{ +2 }$ & $C{ 1 }^{ - }$ ions are $127$ & $76\ oh{ m }^{ -1 }c{ m }^{ -1 }\ e{ q }^{ -1 }$ respectively. Equivalent conductance of $BaCl _{ 2 }$ at infinite dilution is:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. $139.5$

  2. $101.5$

  3. $203$

  4. $279$

Show answer
Correct Option: D
Explanation:

${ \Lambda  } _{ eq }^{ \infty  }\left( { Ba }^{ 2+ } \right) =127{ \Omega  }^{ -1 }{ cm }^{ -1 }{ eq }^{ -1 }\ { \Lambda  } _{ eq }^{ \infty  }\left( { Cl }^{ - } \right) =76{ \Omega  }^{ -1 }{ cm }^{ -1 }{ eq }^{ -1 }\ { \Lambda  } _{ eq }^{ \infty  }\left( { Ba }{ Cl } _{ 2 } \right) ={ \Lambda  } _{ eq }^{ \infty  }\left( { Ba }^{ 2+ } \right) +2{ \Lambda  } _{ eq }^{ \infty  }\left( { Cl }^{ - } \right) \ \qquad \qquad \quad =127+76\times 2\ \qquad \qquad \quad =279{ \Omega  }^{ -1 }{ cm }^{ -1 }{ eq }^{ -1 }$