Tag: extraction of metals by electrolysis

Questions Related to extraction of metals by electrolysis

A solution of ${ AgNO } _{ 3 }$ is a good electrolyte but is not used for electroplating an article with silver because :

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

  1. rapid deposition of silver takes place resulting in uneven coating

  2. slow deposition of silver takes place resulting in uneven coating

  3. poor conduction of silver

  4. none of the above

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Correct Option: A
Explanation:

A solution of $AgNO _3$ is a good electrolyte but is not used for electroplating an article with silver because it undergoes very fast redox process and electroplating done through this process is not uniform.

The electrical process of coating an inexpensive conductor with a metal is called electroplating.

chemistry chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

  1. True

  2. False

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Correct Option: A
Explanation:
Electroplating is a process that uses electric current to deposit/reduce dissolved metal cations so that they form a thin coherent metal coating on an electrode.

It is used to coat a relatively mundane metal, such as copper, with a thin layer of another, more precious metal, such as gold or silver. 

Hence, option $\text{A}$ is correct.

Chromium plating is done to make the object scratch proof and appear shiny.

chemistry chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

  1. True

  2. False

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Correct Option: A
Explanation:

Chromium plating is a technique of electroplating in which a thin layer of chromium is coated onto a metal object. The layer is decorative (shiny), provide corrosion resistance, ease cleaning procedures, and increase surface hardness (scratch resistance).


Hence, option A is correct.

To protect iron from corrosion and rusting , it is electroplated with 

physics chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

  1. Zinc

  2. Chromium

  3. Nickel

  4. Aluminum

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Correct Option: A
Explanation:

Iron is coated with a more active metal like Zinc. This is a sacrificial method. If the rusting conditions are met, zinc rusts before iron and prevents iron from rusting. Zinc makes a protective layer with Zn(OH)2 and ZnCO3

The process of depositing a thin layer of desired metal over another metal by passing an electric current through some electrolyte is called :

chemistry chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

  1. electric shielding

  2. electric polishing

  3. electric coating

  4. electroplating

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Correct Option: D
Explanation:

Electroplating is the application of electrolytic cells in which a thin layer of metal is deposited onto an electrically conductive surface.


Hence, option D is correct.

Electroplating does not help

physics chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

  1. fine finish to the surface

  2. shining appearance

  3. metals to become hard

  4. protect metals against corrosion

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Correct Option: C
Explanation:

Electroplating is primarily used to change the surface properties of an object like appearance, corrosion protection, lubricity etc.  Thus, electroplating does not help in making the metals become hard. 

Chromiumhas a shiny appearance and lt does not corrode

physics chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient

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Correct Option: A
Explanation:

Answer is A.
Electroplating is a very useful process. It is widely used in industry for coating metal objects with a thin layer of a different metal. The layer of metal deposited has some desired property, which the metal of the object lacks. For example, chromium plating is done on many objects such as car parts, bath taps, kitchen gas burners, bicycle handlebars, wheel rims and many others.
Chromium has a shiny appearance. It does not corrode. It resists scratches. However, chromium is expensive and it may not be economical to make the whole object out of chromium. So the object is made from a cheaper metal and only a coating of chromium over it is deposited.
Hence, electroplating of chromium is done on objects like water taps and cycle bell to give them a shiny appearance and prevent them from corrosion. The statement is true.

In electroplating of silver spoon with gold ,silver spoon will act as :

physics chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

  1. anode

  2. cathode

  3. positively charged electrode

  4. none of these

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Correct Option: B
Explanation:

The object on which we have to deposit a material, should always be at cathode

In electroplating of a silver spoon with gold,the gold plate is taken as:

physics chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

  1. negatively charged electrode

  2. cathode

  3. anode

  4. All of the above

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Correct Option: C
Explanation:

The material which should be deposited on the object is always at anode.

In electroplating of the silver spoon with gold, the silver spoon is cleaned with a dilute acid solution to remove the  _________  from its surface.

physics chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

  1. oxide layer

  2. chloride layer

  3. silver layer

  4. gold layer

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Correct Option: A
Explanation:

The silver spoon is cleaned with a dilute acid solution to remove the oxide layer from its surface and washed in running water until it is free from the acid.