Tag: applications of electrolysis

Quizzes (0) Questions (84)

Questions Related to applications of electrolysis

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

Calculate the mass of Ag deposited at cathode when a current of 2A was passed through a solution of $Ag{ NO } _{ 3 }$ for 15 min.
(Given : Molar mass of $Ag = 108\ g\ { mol }^{ -\ 1 }$ $\ 1F=96500\ C\ { mol }^{ -1 }$).

  1. $3.015\ g$
  2. $2.015\ g$
  3. $4.2\ g$
  4. $3.1\ g$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given:

Molar Mass of Ag = 108 g/mol

$1F = 96500\ C mol^{−1}$

Reaction at cathode = $Ag + e^-  \rightarrow   Ag(s)$ 

$w = Zlt$

Where, w = Mass deposited at cathode

Z = electrochemical constant

I = current

t = time

Now I = 2amp

$t = 15\ min = 15\times 60 = 900\ seconds$

Z = Eq. wt of substance $/ 96500 = 108/96500$ 

So,

$w = \dfrac{108}{96500} \times 900 \times 2 $

= $2.015g$

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

The electrochemical equivalent of silver is $0.0011180g$. When an electric current of $0.5$ ampere is passed through an aqueous silver nitrate solution for $200sec$, the amount of silver deposited is:

  1. $1.1180g$
  2. $0.11180g$
  3. $5.590g$
  4. $0.5590g$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to the data given when $1$ e is passed the amount of silver,

deposited is $0.0011180\,g$
$\therefore (0.5\times 200)c$ is passed
then $(0.0011180\times 100)g$
of silver gets deposited 
$=0.11180\,g$

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

$H _2(g)$ and $O _2(g)$ , can be produced by the electrolysis of water. What total volume (in $L$) of $O _2$ and $H _2$ are produced at $STP$ when a current of $30$ A is passed through a $K _2SO _4\, (aq)$  solution for 193 minutes?

  1. 20.16

  2. 40.32

  3. 60.48

  4. 80.64
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total charge passed is Q = I * t = 30 A * (193 * 60 s) = 347400 C. The moles of electrons transferred are n(e-) = Q / F = 347400 / 96500 = 3.6 mol. From the electrolysis of water, 2 moles of electrons produce 1 mole of gas total (0.5 mol O2 and 1 mol H2 per 2 moles of electrons, meaning 3 moles of total gas per 4 moles of electrons; specifically, 4 e- give 1 mole O2 (22.4 L) and 2 moles H2 (44.8 L)). Scaling by 3.6 mol of electrons gives (3.6 / 4) * 3 * 22.4 = 60.48 L total gas at STP.

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

During the mid ninteenth century, Daguerro-type portraits were very popular. A portrait image of a person was made on silver plated copper by developing the image with ?

  1. Silver bromide

  2. Mercury vapour

  3. 'Hypo' (sodium hypochlorite)

  4. An iodine solution
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The latent image was developed to visibility by several minutes of exposure to the forms given off by heated mercury in purpose made developing box.
So development process of Daguerro-type portraits is done with Mercury Vapour.
Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

Silver can be spread as a thin sheet on another metal by electroplating. The film of silver sticks strongly to the metal. Which of the following metals cannot be properly plated with silver?

  1. Copper

  2. Iron

  3. Nickel

  4. Brass
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Iron cannot be property plated with silver it becomes peel if plated with silver are to peeling of silver it cannot properly plated iron.

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

In electroplating of copper by silver, the silver acts as an :

  1. anode

  2. cathode

  3. electrode

  4. electrolyte
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Silver plating on Steel spoon: A silver rod is made as anode and steel spoon as cathode. Potassiumargentocyanide $(K[Ag(CN) _2])$ is used as electrolyte.
$AgNO _3$ is not used as electrolyte because in that case the silver coating will be non-uniform as the electrolysis takes place rapidly.
In electroplating of copper by silver, silver rod is taken as anode.

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

 In the silver plating of copper, $K[Ag(CN) _2]$ is used instead of $AgNO _3$. The reason is:

  1. a thin layer of Ag is formed on Cu

  2. more voltage requirement
  3. $Ag^+$ ions are completely removed from solution
  4. less availability of $Ag^+$ ions, as Cu cannot displace Ag from $[Ag(CN) _2]^-$ ion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Option D is correct 

less avaibality of $Ag+$ions as, $Cu$ cannot displace $Ag$ from $[Ag(CN) _2]$
$Cu$ can replace $Ag$ in $AgNO _3$. But In coordination compound $Ag$ can't be replaced.

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

In $Ag$ - $CuSO _{4}$ cell, silver electrode will serve as:

  1. anode

  2. cathode

  3. both anode and cathode

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
In $Ag - CuSO _4$ cell, silver electrode will serve as cathode, as reduction occurs here and silver metal is deposited. Copper being high in the reactivity series than silver, undergoes oxidation, and silver ions undergo reduction.