Calculate the emf of the cell in which of the following reaction takes place: Ni(s) + 2Ag^+ (0.002 M) \rightarrow Ni^{2+} (0.160 M) + 2Ag(s) [Given that E^{\circ}_{cell} = 1.05 V ]

Given, [Ag^+]=0.002M [Ni^{2+}]=0.160M n=2 According to Nernst equation: E_{cell}=E^0-\dfrac{0.0591}{2}\log \dfrac{[Ni^{2+}]}{[Ag^+]^2} \therefore E_{cell}=1.05-\dfrac{0.0591}{2}\log \dfrac{0.160}{(0.002)^2} \therefore E_{cell}=1.05-0.02955\, \log{(4\times 10^4)} \therefore E_{cell}=0.91V Hence, the correct option is \text{B}

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>>Class 12
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>>Electrochemistry
>> $Electrolytic Cells and Electrolysis$

Electrolytic Cells and Electrolysis

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Q: In electrolysis of water: (a) Name the gas collected at cathode and anode.(b) Why is volume of one gas collected at one electrode is double of anode?(c) Why are few drops of dilute H_2SO_4 added to water?

a) At cathode, H_2 is evolved and at anode O_2 is evolved.b) At cathode, H^+ ion takes two electron to convert itself into H_2 gas. 2 moles of H^+ gives 1 mole of H_2 . 2H^+(aq)+ 2e^- \rightarrow H_2(g) At anode, OH^- ion releases two electrons to convert into water and O_2 . 2 mole OH^- gives 0.5 mole O_2 , i.e why volume of one gas collected at one electron is double of another.c) Acid is added to make the water conduct electricity as the distilled water is a non-conductor of electricity.

Q: How many electrons are there in one coulomb of electricity?

Change on 1e^-=1.602\times 10^{-19} C If total charge =1 C \therefore Total no. of e^-=\cfrac{1}{1.602\times 10^{-19}}=6.24\times 10^{18}e^- Hence, the correct option is (C) .

Q: A metal carbonate X on reacting with an acid gives a gas which when passed through a solution gives the carbonate black. On the other hand, A gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives compound Z, used for disinfecting water. Identify X, Y, G and Z.

According to the problem:Here, X is calcium carbonate \left( {CaC{O_3}} \right) . Y is slaked lime. Z is bleaching powder \left( {CaOC{l_2}} \right) G is chlorine gas. Hence the reactions are involved,

Q: How much electricity in terms of Faraday is required to produce:(i) 20\ g of Ca from molten CaCl_{2} (ii) 40\ g of Al from molten Al_{2}O_{3} [Given : Molar mass of calcium & Aluminium are 40 g mol^{-1} & 27 g mol^{-1} respectively]

(1) \displaystyle Ca^{2+} + 2e^- \rightarrow Ca 1 mole ( 40 g) of Ca will require 2 F of electricity. 20 g ( 0.5 mole) of Ca will require 1 F of electricity.(2) \displaystyle Al^{3+} + 3e^- \rightarrow Al 1 mole ( 27 g) of Al will require 3 moles of electrons. 40 g of Al will require \displaystyle \dfrac {3 \times 40F}{27} = 4.4 F

Q: How much charge is required for the following reductions?(i) 1\ mol of Al^{3+} to Al (ii) 1\ mol of Cu^{2+} to Cu (iii) 1\ mol of {MnO_4}^{-} to Mn^{2+}

Al^{3+} + 3e^-\rightarrow Al The reduction will require 3 Faraday of electricity or \displaystyle 3 \times 96500 = 2.895 \times 10^5 \: C . Cu^{2+} + 2e^-\rightarrow Cu The reduction will require 2 Faraday of electricity or \displaystyle 2 \times 96500 = 1.93 \times 10^5 \: C . {MnO_4}^{-} + 5e^- \rightarrow Mn^{2+} The reduction will require 5 Faraday of electricity or \displaystyle 5 \times 96500 = 4.825 \times 10^5 \: C .Note: 1 mole of electron has a charge of 1 faraday.

Q: During the electrolysis of molten sodium chloride, the time required to produce 0.10 mol of chlorine gas using a current of 3 amperes is:

2Cl^{-}\rightarrow Cl_2+2e^{-} W=\dfrac{E}{96500}\times t 0.1\times71= \dfrac{35.5}{96500}\times 3 = 6433.33 \ sec = 107.22\ min= 110\ min Hence, option D is correct.

Q: A solution of Ni(NO_{3})_{2} is electrolysed between platinum electrodes using a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode?

Given I = 5A Time = 20 \times 60 = 1200\,\,s \therefore Charg e = current \times time \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 5 \times 1200 \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 6000\,\,C According to the reaction. N{i^{2 + }}\left( {aq.} \right) + 2e \to Ni\,\left( s \right) Nickel\,\,deposite\,by\, (2 \times 96487)\,C = 58.7\,\,g \therefore Nickel\,deposite\,by\ 6000\,C = \dfrac{{58.7 \times 6000}}{{2 \times 96487}} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \quad= 1.825\,\,g \therefore Hence 1.825\,g of nickel will be deposited at the cathode.

Q: How much electricity is required in coulomb for the oxidation of:(i) 1\ mol of H_{2}O to O_{2} ?(ii) 1\ mol of FeO to Fe_{2}O_{3} ?

(i) \displaystyle H_2O \rightarrow 2H^+ + \dfrac{1}{2}O_2 + 2e^- Oxidation of one mole of water will require \displaystyle 2 \times 96500 = 1.93 \times 10^5 \: C .(ii) \displaystyle Fe^{2+} \rightarrow Fe^{3+} Oxidation of one mole of \displaystyle Fe^{2+} will require \displaystyle 1 \times 96500 = 96500 \: C \displaystyle .

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Important Questions

Calculate the emf of the cell in which of the following reaction takes place:

$N i (s) + 2 A g^{+} (0.002 M) \to N i^{2 +} (0.160 M) + 2 A g (s)$

[Given that $E_{c e l l}^{\circ} = 1.05 V$ ]

Medium

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In electrolysis of water:

(a) Name the gas collected at cathode and anode.
(b) Why is volume of one gas collected at one electrode is double of anode?
(c) Why are few drops of dilute $H_{2} S O_{4}$ added to water?

Medium

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How many electrons are there in one coulomb of electricity?

Medium

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A metal carbonate X on reacting with an acid gives a gas which when passed through a solution gives the carbonate black. On the other hand, A gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives compound Z, used for disinfecting water. Identify X, Y, G and Z.

Medium

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How much electricity in terms of Faraday is required to produce:

(i) $20 g$ of $C a$ from molten $C a C l_{2}$
(ii) $40 g$ of $A l$ from molten $A l_{2} O_{3}$

[Given : Molar mass of calcium & Aluminium are 40 g $m o l^{- 1}$ & 27 g $m o l^{- 1}$ respectively]

Medium

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How much charge is required for the following reductions?

(i) $1 m o l$ of $A l^{3 +}$ to $A l$
(ii) $1 m o l$ of $C u^{2 +}$ to $C u$
(iii) $1 m o l$ of $M n O_{4}^{-}$ to $M n^{2 +}$

Medium

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During the electrolysis of molten sodium chloride, the time required to produce 0.10 mol of chlorine gas using a current of 3 amperes is:

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A solution of $C u S o_{4}$ is electrolysed for 10 minutes with a current of 1.5 amperes. What is the mass of copper deposited at the cathode?

Medium

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A solution of $N i (N O_{3})_{2}$ is electrolysed between platinum electrodes using a current of $5$ amperes for $20$ minutes. What mass of $N i$ is deposited at the cathode?

Medium

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How much electricity is required in coulomb for the oxidation of:
(i) $1 m o l$ of $H_{2} O$ to $O_{2}$ ?
(ii) $1 m o l$ of $F e O$ to $F e_{2} O_{3}$ ?

Medium

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Electrolytic Cells and Electrolysis

Faraday's Law

Products of Electrolysis

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Introduction to Electrolysis

Faraday Second Law of Electrolysis

Important Questions

Calculate the emf of the cell in which of the following reaction takes place: Ni(s)+2Ag+(0.002M)→Ni2+(0.160M)+2Ag(s) [Given that Ecell∘​=1.05V]

In electrolysis of water: (a) Name the gas collected at cathode and anode. (b) Why is volume of one gas collected at one electrode is double of anode? (c) Why are few drops of dilute H2​SO4​ added to water?

How many electrons are there in one coulomb of electricity?

A metal carbonate X on reacting with an acid gives a gas which when passed through a solution gives the carbonate black. On the other hand, A gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives compound Z, used for disinfecting water. Identify X, Y, G and Z.

How much electricity in terms of Faraday is required to produce: (i) 20 g of Ca from molten CaCl2​ (ii) 40 g of Al from molten Al2​O3​ [Given : Molar mass of calcium & Aluminium are 40 g mol−1 & 27 g mol−1 respectively]

How much charge is required for the following reductions? (i) 1 mol of Al3+ to Al (ii) 1 mol of Cu2+ to Cu (iii) 1 mol of MnO4​− to Mn2+

During the electrolysis of molten sodium chloride, the time required to produce 0.10 mol of chlorine gas using a current of 3 amperes is:

A solution of CuSo4​ is electrolysed for 10 minutes with a current of 1.5 amperes. What is the mass of copper deposited at the cathode?

A solution of Ni(NO3​)2​ is electrolysed between platinum electrodes using a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode?

How much electricity is required in coulomb for the oxidation of: (i) 1 mol of H2​O to O2​? (ii) 1 mol of FeO to Fe2​O3​?

Calculate the emf of the cell in which of the following reaction takes place:

$N i (s) + 2 A g^{+} (0.002 M) \to N i^{2 +} (0.160 M) + 2 A g (s)$

[Given that $E_{c e l l}^{\circ} = 1.05 V$ ]

In electrolysis of water:

(a) Name the gas collected at cathode and anode.
(b) Why is volume of one gas collected at one electrode is double of anode?
(c) Why are few drops of dilute $H_{2} S O_{4}$ added to water?

How much electricity in terms of Faraday is required to produce:

(i) $20 g$ of $C a$ from molten $C a C l_{2}$
(ii) $40 g$ of $A l$ from molten $A l_{2} O_{3}$

[Given : Molar mass of calcium & Aluminium are 40 g $m o l^{- 1}$ & 27 g $m o l^{- 1}$ respectively]

How much charge is required for the following reductions?

(i) $1 m o l$ of $A l^{3 +}$ to $A l$
(ii) $1 m o l$ of $C u^{2 +}$ to $C u$
(iii) $1 m o l$ of $M n O_{4}^{-}$ to $M n^{2 +}$

A solution of $C u S o_{4}$ is electrolysed for 10 minutes with a current of 1.5 amperes. What is the mass of copper deposited at the cathode?

A solution of $N i (N O_{3})_{2}$ is electrolysed between platinum electrodes using a current of $5$ amperes for $20$ minutes. What mass of $N i$ is deposited at the cathode?

How much electricity is required in coulomb for the oxidation of:
(i) $1 m o l$ of $H_{2} O$ to $O_{2}$ ?
(ii) $1 m o l$ of $F e O$ to $F e_{2} O_{3}$ ?