Tag: electroplating

Questions Related to electroplating

The same amount of electricity was passed through two separate electrolytic cells containing solutions of nickel nitrate $\left[ Ni{ \left( { NO } _{ 3 } \right)  } _{ 2 } \right]$ land chromium nitrate $\left[Cr{ \left( { NO } _{ 3 } \right)  } _{ 3 } \right]$ respectively. If $0.3g$ of nickel was deposited in the first cell, the common of chromium deposited is :
$(at. Wt. Of Ni=59, at. Wt. Of Cr=52)$

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. $0.1g$

  2. $0.17g$

  3. $0.3g$

  4. $0.6g$

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Correct Option: B

A certain quantity of electricity when passed through solution of ${ AgNO } _{ 3 }$, ${ ZnSO } _{ 4 }$, ${ CrI } _{ 3 }$. If X moles of Cr are deposited at its cathode, how many moles of Ag and Zn are deposited at their respective cathodes.

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. X, X

  2. 3X, 2X

  3. 3X, 1.5X

  4. none of these

Show answer
Correct Option: C
Explanation:

$Ag^++e^- \longrightarrow Ag$

$Zn^{2+}+2e^- \longrightarrow Zn$
$Cr^{3+}+3e^-\longrightarrow Cr$
Given that $x$ moles of $Cr$ is deposited at it's cathode means in case of $Ag$ it will be $3X$  and for $Zn$ it will be $\cfrac {3X}{2}$ moles deposits at cathode.

How long (approximate) should water be electrolysed by passing through $100$ amperes current so that the oxygen realised can completely burn $27.66\ g$ of diborane?


(Atomic weight of $B=10.8\ u$ )

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. $0.8$ hours

  2. $3.2$ hours

  3. $1.6$ hours

  4. $6.4$ hours

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Correct Option: B

The mass of carbon anode consumed (giving only carbondioxide) in the production of 270 kg of Aluminium metal from bauxite by the Hall process is :

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. 270 kg

  2. 540 kg

  3. 90 kg

  4. 180 kg

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Correct Option: B

The same amount of electricity was passed through two separate electrolytic cells containing solutions of nickel nitrate $[Ni(NO _{3}) _{2}$] and chromium nitrate $[Cr(NO _{3}) _{3}$] respectively.If 0.3 g of nickel was deposited in the first cell, the amount of chromium deposited is:
(at.wt of Ni=59, at. wt. of Cr=52)

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. 0.1 g

  2. 0.17 g

  3. 0.3 g

  4. 0.6 g

Show answer
Correct Option: C

On electrolysing a solution of dilute ${ H } _{ 2 }{ SO } _{ 4 }$ between platinum electrodes, the gas evolved at the anode is 

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. ${ SO } _{ 2 }$

  2. ${ SO } _{ 3 }$

  3. ${ O } _{ 2 }$

  4. ${ H } _{ 2 }$

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Correct Option: A

In the manufacture of $NaOH$ by the electrolysis of $NaCl$ solution, the cathode and anode are separated using a diaphragm because :

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. it prevents the reaction betweeen ${H _2}$ and $C{l _2}$ formed

  2. it prevents the mixing of $NaOH$ and $NaC{l _2}$

  3. it prevents the reaction betweeen $Na$ and $C{l _2}$ formed

  4. it increases the yield of $NaOH$

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Correct Option: B

Charge required for liberating $710 g$ of $Cl _{2}(g)$ by electrolyzing a concentrated solution of $NaCl$ will be:

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. $1.93$ x $10^{5}$ $C$

  2. $1.93$ x $10^{6}$ $C$

  3. $9.65$ x $10^{6}$ $C$

  4. $9.65$ x $10^{5}$ $C$

Show answer
Correct Option: B
Explanation:

The reaction taking place at anode is given by:

$2Cl^- \rightarrow Cl _2+2e^-$
Thus, $2$ moles of $e^-$ are required to liberate $1$ mole of $Cl _2$
Moles of $Cl _2=\dfrac{710}{71}=10$
Hence moles of $e^-$ required $=2\times10=20$
Hence $Q=20F$
$\Rightarrow Q=20\times 96500$
$\Rightarrow Q=1.93\times10^6 C$

The correct relation is

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. $\triangle G = -RT\ ln\ K/Q$

  2. $\triangle G = -RT\ ln\ K$

  3. $\triangle G = -RT\ ln\ Q/K$

  4. $\triangle G = +RT\ ln\ Q$

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Correct Option: B
Explanation:

$\triangle G = \triangle G^{\circ} + RT\ ln Q$
$\triangle G = -RT\ ln \dfrac {K}{Q}$.

Which process occurs in the electrolysis of an aqueous solution of nickel chloride at nickel anode?

chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. $Ni\rightarrow Ni^{2+}+2e^{-}$

  2. $Ni^{2+}+2e^{-}\rightarrow Ni$

  3. $2CI^{-}\rightarrow 2CI _{2}+2e^{-}$

  4. $2H^{+}+2e^{-}\rightarrow H _{2}$

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Correct Option: A