Tag: extraction of metals by electrolysis

Questions Related to extraction of metals by electrolysis

State True or False:
Rusting of iron is a physical change.

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

  1. True

  2. False

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Correct Option: B

Which of the following is the preferred electrolyte for silver plating?

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

  1. $AgCl+HCl$

  2. $Ag{NO} _{3}+H{NO} _{3}$

  3. ${Ag} _{2}{SO} _{4}$

  4. $AgCN+NaCN$

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Correct Option: D
Explanation:

Silver plating is an electroplating process utilizing an electrolyte containing silver cyanide solution and some free cyanide ions and operating at pH value not less than $8$. Free cyanide prevents precipitation of silver cyanide salt from the solution, provides electrical conductivity of the electrolyte and helps in the dissolution of silver anodes.

Why is electroplating done?

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

  1. to increase attractiveness

  2. to purify an impure metal

  3. to prevent rusting

  4. all of the above

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Correct Option: A,C

Electroplating is a process of deposition of ________ metal on the surface of _________ metal.

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

  1. inferior, superior

  2. superior, superior

  3. inferior, inferior

  4. superior, inferior

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Correct Option: D
Explanation:

Electroplating is a process of deposition of superior metal on the surface of inferior metal.

Anode is the _________ block and cathode is the _________ block in electrorefining of metal.

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

  1. impure, pure

  2. pure, pure

  3. impure, impure

  4. pure, impure

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Correct Option: A
Explanation:

Anode is the impure block and cathode is the pure block in electro-refining of metal.

Electroplating is ________________ of metals and electro-refining is ___________ of metals.

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

  1. depositing, refining

  2. plating, extracting

  3. refining, depositing

  4. none of the above

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Correct Option: A
Explanation:

Electroplating is $depositing$ of metals and electro-refining is $refining$ of metals.

The main applications of electrolysis are:

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

  1. electroplating

  2. electrorefining

  3. extraction of metals

  4. All of the above

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Correct Option: D
Explanation:

The main application of electrolysis are:


Electroplating: Electroplating is a process of depositing a layer of any desired metal on another material by means of electricity.

Electrorefining: Electrorefining refers to the process of using electrolysis to increase the purity of a metal extracted from its ore.

Extraction of metals: Extractions are a way to separate the desired substance when it is mixed with others. 

Hence, option D is correct.

Which one of the following is not a main application of electrolysis?

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

  1. Electrorefining

  2. Electrode cleaning

  3. Extraction of metals

  4. Electroplating

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Correct Option: B
Explanation:

The main application of electrolysis are:

  • Electrorefining
  • Electroplating
  • Extraction of metals

When an external current is used to induce a non-spontaneous redox reaction, the process is called ________.

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

  1. neutralization

  2. hydrolysis

  3. electrolysis

  4. esterification

  5. galvanization

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Correct Option: C
In an electroplating experiment with a $Cu^{2+}$ solution, $10.0$ amp is applied for $965\ sec$. How many moles of $Cu$ will be plated?
chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

  1. $0.05\ \text{moles}$

  2. $0.1\ \text{moles}$

  3. $0.001\ \text{moles}$

  4. $0.005\ \text{moles}$

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Correct Option: A
Explanation:
$w = {Z\times I\times t}$

$w = \dfrac{E\times I\times t}{96500}$

$w = \dfrac{Molecular\ weight \times I\times t}{2\times 96500}$                                                 [$\therefore E= M/n$]

n=2

$n = \dfrac{w}{M} = \dfrac{I\times t}{2\times 96500}$

$ n=$ $\dfrac{10\times 965}{2\times 96500} = 0.05\ moles$

Hence, option A is correct.