NCERT Solutions for Class 12 Chemistry Chapter 2 - Electrochemistry

NCERT Solutions for Class 12 Chemistry Chapter 2 - Electrochemistry

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CBSE Class 12th Exam Date:17 Feb' 26 - 17 Feb' 26

Shivani PooniaUpdated on 26 Sep 2025, 06:05 PM IST

Have you ever wondered how batteries work and why metals corrode? The answer to all these questions lies in "Electrochemistry". It is a branch of chemistry that explores the relation between electrical energy and chemical reactions. In Class 12th Chemistry Chapter 2- Electrochemistry, students get to learn about the Nernst equation, electrode potential, EMF, how cells produce current, and how processes like electroplating and electrolysis are carried out.

This Story also Contains

  1. NCERT Solutions for Class 12 Chemistry Chapter 2 Download PDF
  2. NCERT Solutions Of Class 12 Chemistry Chapter 2 (Intext Questions 2.1 to 2.15)
  3. NCERT Solutions for Class 12 (Exercise Questions)
  4. Class 12 Chemistry NCERT Chapter 2: Higher Order Thinking Skill (HOTS) Questions
  5. Approach to Solve Questions of Chapter 2
  6. Topics of NCERT Class 12 Chemistry Chapter 2
  7. What Extra Should Students Study Beyond NCERT for JEE?
  8. Formulas Of NCERT Class 12 Chemistry Electrochemistry
  9. NCERT Solutions for Class 12 Chemistry
  10. NCERT Exemplar Class 12 Solutions Subject-wise
  11. NCERT Solutions for Class 12 Subject-wise
NCERT Solutions for Class 12 Chemistry Chapter 2 - Electrochemistry
NCERT Solutions for Class 12 Chemistry Chapter 2

Our subject experts have designed the NCERT solutions for class 12 chemistry of Chapter -2 to provide a systematic and structured approach to these important concepts. Through a combination of solved examples and clear conceptual explanations, these solutions help students develop a clear understanding of critical concepts. These NCERT solutions are a valuable resource to enhance performance in board exams as well as in competitive exams like JEE Advanced, NEET, JEE, etc. You can also check the HOTS questions given in this article to enhance critical thinking and deepen your understanding of the topic.

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NCERT Solutions for Class 12 Chemistry Chapter 2 Download PDF

Students can download the NCERT Solutions for Chapter 2 in PDF format for free. These solutions are designed to help you understand the fundamental concepts and solve textbook questions with ease.

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NCERT Solutions Of Class 12 Chemistry Chapter 2 (Intext Questions 2.1 to 2.15)

Here are detailed and accurate NCERT solutions for Intext Questions of Class 12 Chemistry Chapter 2. These solutions will help in better concept clarity and exam preparation.

Page 36

Question 2.1 How would you determine the standard electrode potential of the system Mg2+|Mg ?
Answer:

To determine the standard electrode potential of the given system, we need to use a hydrogen electrode. In the setup, we shall put a hydrogen electrode as the cathode and Mg | MgSO4 as the anode.

Mg | Mg 2 + ( aq , 1 M ) | | H + ( aq , 1 M ) | H 2 ( g , I bar ) , Pt ( s )

Now we will measure the emf of the cell. This emf will be the standard electrode potential of the magnesium electrode.

E°cell = E° right – E°left
E°left =0 ( The standard hydrogen electrode is always zero)
Hence
E o c e l l = E o M g | M g 2 +

Question 2.2 Can you store copper sulphate solutions in a zinc pot?

Answer:

The standard electrode potential of Zinc is - 0.76 whereas that of Copper is 0.34. So Zinc will reduce copper into the lower state.

It is known that zinc is more reactive than copper. Thus if we will store copper sulphate solution in zinc pot then zinc will displace copper from its solution.

The following reaction will take place:-

Z n + C u S O 4 → Z n S O 4 + C u

Question 2.3 Consult the table of standard electrode potentials and suggest three substances that can oxidise ferrous ions under suitable conditions.

Answer:

The oxidising strength of elements increases as the standard electrode potential increases.

So all the elements having greater standard potential than iron can oxidise it to a higher state.

Few such elements are :- F2 , Cl2, Br2, Ag+1etc.

Page 41

Question 2.4 Calculate the potential of hydrogen electrode in contact with a solution whose pH is 10.

Answer:

It is given that pH of the solution is 10,i.e., the hydrogen ion concentration in the solution is 10 -10 M.

H + + e − ⟶ 1 2 H 2

By Nernst equation we have :-

E C e l l = E c e l l ∘ − R T 2 F l n 1 [ H + ]

So, = 0 − 0.0591 1 l o g 1 [ 10 − 10 ]

or = − 0.591 V

So the required potential is - 0.591 V.

Question 2.5 Calculate the emf of the cell in which the following reaction takes place: Ni(s)+2Ag+(0.002M)→Ni2+(0.160M)+2Ag(s) Given that E(cell)Θ=1.05V

Answer:

Here we can directly apply the Nernst equation :-

E C e l l = E c e l l ∘ − 0.0591 n l o g [ N i + 2 ] [ A g + ] 2

Putting the value in this equation :-

= 1.05 − 0.0591 2 l o g 0.160 ( 0.002 ) 2

= 1.05 − 0.02955 l o g ( 4 × 10 4 )

= 0.914 V

Hence the required potential is 0.914 V.

Question 2.6 The cell in which the following reaction occurs:
2Fe3+(aq)+2I−(aq)→2Fe2+(aq)+I2(s) has Ecell0=0.236V at 298K.
Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.

Answer:

For finding Gibbs free energy we know the relation :-

Δ G r ∘ = − n F E c e l l ∘

= − 2 × 96487 × 0.236

= − 45541.864 J m o l − 1

= − 45.54 K J m o l − 1

Now, for equilibrium constant we will use :-

Δ G r ∘ = − 2.303 R T l o g K c

So, l o g K c = − − 45.54 × 10 3 2.303 × 8.314 × 298

l o g K c = 7.981

K c = 9.57 × 10 7

Page 51

Question 2.7 Why does the conductivity of a solution decrease with dilution?

Answer:

The conductivity of a solution depends upon the number of ions and the distance between them. In the process of dilution, we don't increase the number of ions in the solution instead we increase the distance between them. So the conductivity of the solution decreases due to dilution.

Question 2.8 Suggest a way to determine the Λm0 value of water.

Answer:

We know :

Λ m = Λ m ∘ − A c 1 2

If we draw a straight line between Λ m and c , its slope will be -A and the intercept on the y-axis will be Λ m ∘ .

In this way, we can obtain the value of limiting molar conductivity.

Question 2.9 The molar conductivity of 0.025molL−1 methanoic acid is 46.0Scm2Scm2mol−1 Calculate its degree of dissociation and dissociation constant. Given λ0(H+)=349.6Scm2mol−1 and λ0(HCOO−)=54.6Scm2mol−1

Answer:

We know that :-

Λ m = λ ∘ ( H + ) + λ ∘ ( H C O O − )

= 349.6 + 54.6

= 404.2 S c m 2 m o l − 1

For degree of dissociation, we have :-

α = Λ m ( H C O O H ) Λ ∘ ( H C O O H )

or α = 46.1 404.2 = 0.114

For dissociation constant, we have :-

K a = c α 2 1 − α

or K a = 0.025 × ( 0.114 ) 2 1 − 0.114

or = 3.67 × 10 − 4 m o l L − 1

Page no 54

Question 2.10 If a current of 0.5 ampere flows through a metallic wire for 2 hours, then how many electrons would flow through the wire?

Answer:

Firstly we will find total charge flown through the wire then we will calculate number of electrons.

We are given :- I = 0.5 A, Time = 2 hours = 7200 seconds.

We have, Q = I.t

= (0.5)7200 = 3600 C.

Now we will convert charge into number of electrons.

We know that 96487 C = 6.023 × 10 23 N o . o f e l e c t r o n s

So toal number of electrons :

= 3600 96487 × 6.023 × 10 23

or = 2.25 × 10 22 no. of electrons will flow through wire.

Question 2.11 Suggest a list of metals that are extracted electrolytically.

Answer:

Metals like Na, Mg, Al, etc. are produced on a large scale by electrochemical reduction of their respective cations or by the process electrolysis because there are no suitable reducing agents available for this purpose.

Question 2.12 Consider the reaction: Cr2O72−+14H++6e−→2cr3++7H2O
What is the quantity of electricity in coulombs needed to reduce 1 mol of Cr2O72− ?

Answer:

It is clear from the given reaction that reduction of 1 mol of Cr2O72- will be

= 6 F (as 6 electrons are required to balance the reaction; Charge required = nF)

= 6 × 96500

= 579000 C

Thus 578922 C charge is required for reduction of 1 mol of Cr2O72- .

Page no 58

Question 2.13 Write the chemistry of recharging the lead storage battery, highlighting all the materials that are involved during recharging.

Answer:

The lead storage battery can be recharged by reversing the direction of current passing through it.

For recharging PbSO4 is converted into Pb at the anode and into PbO2 at the cathode.

The chemical reactions are as follows:-

1643888556447

Question 2.14 Suggest two materials other than hydrogen that can be used as fuels in fuel cells.

Answer:

The two materials are methane and methanol that can be used as fuels in fuel cells.

Question 2.15 Explain how rusting of iron is envisaged as setting up of a electrochemical cell.

Answer:

The chemistry of corrosion is quite complex but it can be understood by considering it as an electrochemical phenomenon. Consider a particular spot on an object where corrosion takes place. At here oxidation takes place and this spot behaves as the anode. The released electrons at anodic spot go through the metal and go to another spot on the metal and reduction of oxygen takes place in the presence of H+. This spot behaves as a cathode with the reaction. In this way this analogy is possible.

NCERT Solutions for Class 12 (Exercise Questions)

Here are detailed and accurate NCERT solutions for Exercise Questions of Class 12 Chemistry Chapter 2. These solutions will help in better concept clarity and exam preparation.

Question 2.1 Arrange the following metals in the order in which they displace each other from the solution of their salts.
Al, Cu, Fe, Mg and Zn.

Answer:

The order in which metals displace each other from the solution of their salts can be given with the help of their standard electrode potential. Since magnesium has the least standard electrode potential so it is the most strong reducing agent. So the required order we get is:-

M g > A l > Z n > F e > C u

Question 2.2 Given the standard electrode potentials,

K + / K = − 2.93 V , A g + / A g = 0.80 V ,

H g 2 + / H g = 0.79 V

M g 2 + / M g = − 2.37 V , C r 3 + / C r = − 0.74 V

Arrange these metals in their increasing order of reducing power.

Answer:

Elements with reducing power or reducing agents have least/minimum standard electrode potential i.e., reducing power increases with a decrease in standard electrode potential. So the result obtained is:-

K > Mg > Cr > Hg > Ag

Question 2.3 Depict the galvanic cell in which the reaction

Z n ( s ) + 2 A g + ( a q ) → Z n 2 + ( a q ) + 2 A g ( s ) ) takes place. Further show

(i) Which of the electrode is negatively charged?

Answer:

The galvanic cell of the given reaction is depicted below:-

Zn (s) | Zn+2 (aq) || Ag+ (aq) | Ag (s)

Clearly Zn electrode is negatively charged.

Question 2.3 Depict the galvanic cell in which the reaction

Z n ( s ) + 2 A g + ( a q ) → Z n 2 + ( a q ) + 2 A g ( s ) takes place.

(ii) The carriers of the current in the cell.

Answer:

The carriers of current in the cell are ions. and current flows from silver to zinc in the external circuit.

Question 2.3 Depict the galvanic cell in which the reaction Zn(s)+2Ag2+(aq)→Zn2+(aq)+2Ag(s) takes place.

(iii) Individual reaction at each electrode.

Answer:

The reactions taking place at both cathode and anode are shown below:-

(i) Cathode reaction:-

A g ( a q ) + + e − → A g ( s )

(ii) Anode reaction :-

Z n ( s ) → Z n ( a q ) 2 + + 2 e −

Question 2.4 Calculate the standard cell potentials of galvanic cell in which the following reactions take place:

(i) 2 C r ( s ) + 3 C d 2 + ( a q ) → 2 C r 3 + ( a q ) + 3 C d

Calculate the Δ r G 0 and equilibrium constant of the reactions.

Answer:

The galvanic cell of the given reaction is shown below:-

Cr ( s ) | Cr ( aq ) 3 + ‖ Cd ( aq ) 2 + | Cd ( s )

The standard electrode potential of Cr and Cd can be found in table of standard electrode potential.

So, we get :

E ∘ = E R ∘ − E L ∘

= − 0.40 − ( − 0.74 )

= 0.34 V

Now

Δ G r ∘ = − n F E c e l l ∘

Putting values :

Δ G r ∘ = − 6 × 96487 × 0.34

= − 196.83 K J m o l − 1

Now for finding equlilibrium constant we have :

l o g k = − Δ G r ∘ 2.303 × R × T

or l o g k = 34.496

or K = 3.13 × 10 3 4

Question 2.4 Calculate the standard cell potentials of galvanic cell in which the following reactions take place:

(ii). F e 2 + ( a q ) + A g + ( a q ) → F e 3 + ( a q ) + A g ( s )

Calculate the Δ r G e and equilibrium constant of the reactions.

Answer:

The galvanic cell of the given reaction is shown below :-

Fe ( a q ) 2 + | Fe ( a q ) 3 + | | Ag ( a q ) + | Ag ( s )

We can know about the electrode potential of Fe and Ag with the help of table of standard electrode potential.

We have : E ( c e l l ) ∘ = E R ∘ − E L ∘

or = 0.80 − 0.77

or = 0.03 V

Now consider : Δ G r ∘ = − n F E ( c e l l ) ∘

or = − 1 × 96487 × 0.03

= − 2.89 K J m o l − 1

Now for equilibrium constant :

l o g K = − Δ G r ∘ 2.303 × R T

or = − − 2894.61 2.303 × 8.314 × 298

or = 0.5073

Thus k ≈ 3.2

Question 2.5 Write the Nernst equation and emf of the following cells at 298 K:

(i) M g ( s ) | M g 2 + ( 0.001 M ) | | C u 2 + ( 0.000 .1 M ) | C u ( s )

Answer:

The nernst equation gives :

E C e l l = E c e l l ∘ − 0.059 n l o g [ M g 2 + ] [ C u 2 + ]

This gives,

= 0.34 − ( − 2.36 ) − 0.059 2 l o g 0.001 0.0001

= 2.7 − 0.02955

= 2.67 V

So the emf of the cell is 2.67 V.

Question 2.5 Write the Nernst equation and emf of the following cells at 298 K:

(ii) F e ( s ) | F e 2 + ( 0.001 M ) | | H + ( 1 M ) | H 2 ( g ) ( 1 b a r ) | P t ( s )

Answer:

The nernst equation for this gives :

E C e l l = E c e l l ∘ − 0.0591 n l o g [ F e + 2 ] [ H + ] 2

This gives : = 0 − ( − 0.44 ) − 0.0591 2 l o g 0.001 1 2

or = 0.44 − 0.02955 ( − 3 ) = 0.53 V

Thus the emf of the given galvanic cell is 0.53 V.

Question 2.5 Write the Nernst equation and emf of the following cells at 298 K:

(iii) S n ( s ) | S n 2 + ( 0.050 M ) | | H + ( 0.020 M ) | H 2 ( g ) ( 1 b a r ) P t ( s )

Answer:

The nernst equation for this reaction gives :-

E C e l l = E c e l l ∘ − 0.0591 n l o g [ S n + 2 ] [ H + ] 2

Now for emf, just put all the values.

E C e l l = 0 − ( − 0.14 ) − 0.0591 2 l o g 0.050 0.020 2

or = 0.14 − 0.0295 × l o g 125

or = 0.14 − 0.062 = 0.078 V

Thus emf of the cell is 0.078 V.

Question 2.5 Write the Nernst equation and emf of the following cells at 298 K:

(iv) P t ( s ) | B r − ( 0.010 M ) | B r 2 ( 1 ) | | H + ( 0.030 M ) | H 2 ( g ) ( I b a r ) P t ( s )

Answer:

The Nernst equation of the given reaction gives :

E C e l l = E c e l l ∘ − 0.0591 n l o g 1 [ B r − ] 2 [ H + ] 2

or = ( 0 − 1.09 ) − 0.0591 2 l o g 1 ( 0.010 ) 2 ( 0.030 ) 2

or = − 1.09 − 0.02955 × l o g ( 1.11 × 10 7 )

or = − 1.09 − 0.208 = − 1.298 V

So the required emf of the cell is -1.298 V.

Question 2.6 In the button cells widely used in watches and other devices the following reaction takes place:

Z n ( s ) + A g 2 O ( s ) + H 2 O ( l ) → Z n 2 + ( a q ) + 2 A g ( s ) + 2 O H − ( a q )

Determine Δ r G e and E e for the reaction.

Answer:

The given reaction is obtained from :-

Zn ( s ) ⟶ Zn ( a q ) 2 + + 2 e − ; E ⊖ = 0.76 V

Ag 2 O ( s ) + H 2 O ( t ) + 2 e − ⟶ 2 Ag ( s ) + 2 OH ( a q ) − ; E ⊖ = 0.344 V

So the E o cell can be obtained directly.

E c e l l ∘ = 0.76 − ( − 0.344 ) = 1.104 V

Now for free energy calculation, we have :-

Δ G r ∘ = − n F E c e l l ∘

or = − 2 × 96487 × 1.04

or = − 213043.29 J

or = − 213.04 K J

Question 2.7 Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.

Answer:

Conductivity(k) or specific conductance of a solution is defined as the inverse of resistivity.

Mathematically, it can be written as:-

G = κ A L

In the above equation is κ the conductivity of a solution. Thus the definition of conductivity becomes as the conductance of a substance which is 1 cm long and has 1 sq. cm of cross-sectional area.

With dilution conductivity of a solution decreases due to an increase in distance between ions.

Molar conductivity: - It is defined as the conductivity of a solution per unit concentration

i.e., Λ M = κ C

It is clear from the above mathematical expression of the molar conductivity that, if we dilute the solution or decrease its concentration then molar conductivity increases. This is because, on dilution of a solution, a decrease in is κ more than compensated by the increase in its volume.

Question 2.8 The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 S cm-1. Calculate its molar conductivity.

Answer:

We know that the molar conductivity of a solution is defined as:-

Λ M = κ C

Putting the value of conductivity and concentration in the above equation:-

Λ M = 0.0248 × 1000 0.20 = 124 S c m 2 m o l − 1

Question 2.9 The resistance of a conductivity cell containing 0.001M KCl solution at 298 K is 1500 ohm . What is the cell constant if conductivity of 0.001M KCl solution at 298 K is 0.146×10−3 Scm−1 .

Answer:

We are given with conductivity of cell κ = 0.146 × 10 − 3 S c m − 1 and resistance R = 1500 Ω .

Also, Cell constant = κ × R

or = 0.146 × 10 − 3 × 1500

or = 0.219 c m − 1

Question 2.10 The conductivity of sodium chloride at 298 K has been determined at different concentrations and the results are given below:

Calculate Λ m for all concentrations and draw a plot between Λ m and c 1 / 2 . Find the value of Λ m 0 .

Answer:

Given,

κ = 1.237 × 10 − 2 S m − 1 , c = 0.001 M

Then, κ = 1.237 × 10 − 4 S cm − 1 , c 1 / 2 = 0.0316 M 1 / 2

∴ Λ m = k c = 1.237 × 10 − 4 Scm − 1 0.001 molL − 1 × 1000 cm 3 L = 123.7 S cm 2 mol − 1

Given,

κ = 11.85 × 10 − 2 S m − 1 , c = 0.010 M
Then, κ = 11.85 × 10 − 4 S cm − 1 , c 1 / 2 = 0.1 M 1 / 2

∴ Λ m = k c = 11.85 × 10 − 4 Scm − 1 0.010 mol L − 1 × 1000 cm 3 L = 118.5 S cm 2 mol − 1

Given,

κ = 23.15 × 10 − 2 S m − 1 , c = 0.020 M
Then, κ = 23.15 × 10 − 4 S cm − 1 , c 1 / 2 = 0.1414 M 1 / 2

∴ Λ m − k c = 23.15 × 10 − 4 Scm − 1 0.020 mol L − 1 × 1000 cm 3 L = 115.8 S cm 2 mol − 1

Given,

κ = 55.53 × 10 − 2 S m − 1 , c = 0.050 M Then, κ = 55.53 × 10 − 4 S cm − 1 , c 1 / 2 = 0.2236 M 1 / 2 ∴ k = k c = 55.53 × 10 − 4 Scm − 1 0.050 mol L − 1 × 1000 cm 3 L = 111.11 S cm 2 mol − 1

Given,

κ = 106.74 × 10 − 2 S m − 1 , c = 0.100 M
Then, κ = 106.74 × 10 − 4 S cm − 1 , c 1 / 2 = 0.3162 M 1 / 2

∴ Λ m = k c = 106.74 × 10 − 4 S cm − 1 0.100 mol L − 1 × 1000 cm 3 L = 106.74 S cm 2 mol − 1
Now, we have the following data:

c 1 / 2 / m 1 / 20.03160.10.14140.22360.3162
Λ m ( Scm 2 mol − 1 )123.7118.5115.8111.1106.74

Since the line interrupts Λ m at 124.0 S cm 2 mol − 1 , Λ ∘ m = 124.0 S cm 2 mol − 1 .

Question 2.11 Conductivity of 0.00241 M acetic acid is 7.896×10−5Scm−1 . Calculate its molar conductivity. If Δm0 for acetic acid is 390.5Scm2mol−1 , what is its dissociation constant?

Answer:

Molar conductivity of a solution is given by :-

Λ M = κ C

So, = 7.896 × 10 − 5 0.00241 × 1000

or = 32.76 S c m 2 m o l − 1

Also, it is given that Λ m ∘ = 390.5 S c m 2 m o l − 1 .

α = Λ m Λ m ∘

or α = 32.76 390.5

α = 0.084

For dissociation constant we have,

K d = c α 2 ( 1 − α )

so, = 0.00241 × 0.084 2 ( 1 − 0.084 )

or = 1.86 × 10 − 5 m o l L − 1

Question 2.12 How much charge is required for the following reductions:

(i) 1 m o l o f A l 3 + t o A l ?

Answer:

The equation becomes:-

A l + 3 + 3 e − = A l

So required charge is 3F.

Q = n*96500

Q = 3*96500 = 289500 C

Question 2.12 How much charge is required for the following reductions:

(ii) 1 m o l o f C u 2 + t o C u ?

Answer:

The equation can be written as:-

C u 2 + + 2 e − = C u

Thus charge required is = 2 F

= 2 ( 96500 ) = 193000 C

Question 2.12 How much charge is required for the following reductions:

(iii) M n O 4 − t o M n 2 + ?

Answer:

The given reaction can be written as:-

M n + 7 + 5 e − = M n + 2

Thus charge required in above equation = 5 F

= 5 ( 96500 )

= 482500 C

Question 2.13 How much electricity in terms of Faraday is required to produce

(i) 20.0 g of Ca from molten C a C l 2 ?

Answer:

The equation for the question is given by :-

C a 2 + + 2 e − = C a

In this equation, for 1 mol of Ca, 2F charge is required or we can say that for 40 g of Ca charge required is 2F.

So, for 20 g of Ca charge required will be = F = 96500 C.

Question 2.13 How much electricity in terms of Faraday is required to produce

(ii) 40.0 g of AI from molten A l 2 O 3 ?

Answer:

The equation for the given question is :-

A l + 3 + 3 e − = A l

Thus for 1 mol of Al, charge required is 3F.

So the required amount of electricity in terms of charge will be :-

= 3 27 × 40 F = 4.44 F

Question 2.14 How much electricity is required in coulomb for the oxidation of

(i) 1 mol of H 2 O t o O 2 ?

Answer:

According to question the equation of oxidation will be :-

O 2 − → 1 2 O 2 + 2 e −

Thus, for oxidation of O 2- , 2F charge is required.

= 2 × 96500 C

= 193000 C

Question 2.14 How much electricity is required in coulomb for the oxidation of

(ii) 1 mol of F e O t o F e 2 O 3 ?

Answer:

The oxidation equation for the given reaction will be :-

F e + 2 → F e + 3 + e −

So for oxidation of 1 mol F e + 2 charge required = 1 F

= 96500 C

Question 2.15 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?

Answer:

We are given:

I = 5A

and t = 20(60) = 1200 sec.

So total charge = 5(1200) = 6000 C.

The equation for nickel deposition will be:-

N i + 2 + 2 e − → N i

Thus, from 2F charge 58.7 g of nickel deposition takes place.

i.e., 2 ( 96487 ) C → 58.7 g N i

So for 6000 C charge total nickel deposition will be:-

= 58.7 2 × 96487 × 6000

or = 1.825 g

Hence 1.825 g Ni will be deposited in the given conditions.

Question 2.16 Three electrolytic cells A,B,C containing solutions of ZnSO4 , AgNO3 and CuSO4 , respectively are connected in series. A steady current of 1.5 amperes was passed through them until 1.45g of silver deposited at the cathode of cell B. How long did the current flow? What mass of copper and zinc were deposited?

Answer:

Since the cells are connected in series so the current passing through each cell will be equal.(1.5 A)

Now we are given that 1.45 g of silver is deposited. So firstly we will consider the cell containing silver.

A g + + e − → A g

Since for deposition of 108 g silver 96487 C charge is required, thus for 1.45 g deposition of silver charge required will be:-

= 96487 108 × 1.45 = 1295.43 C

Now we can find the time taken by 1.5 A current to deposit 1.45 g silver.

T i m e t a k e n = 1295.43 1.5 ≈ 864 s e c .

For copper:-

C u + 2 + 2 e − = C u

Since 2F charge will deposit 63.5 g of Cu, then deposition by 1295.43 C will be:-

= 63.5 2 × 96487 × 1295.43 = 0.426 g

Hence 0.426 g of copper will be deposited.

For zinc:-

Z n + 2 + 2 e − → Z n

Since 2F charge will deposit 65.4 g of Zn, then deposition by 1295.43 C will be:-

= 65.4 2 × 96487 × 1295.43 = 0.439 g

Hence 0.439 g of zinc will be deposited.

Question 2.17 Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

(i) F e a q 3 + a n d I a q −

Answer:

The concept used here will be that a reaction is feasible only if E c e l l ∘ is positive.

Anode and cathode reactions will be as follows:-

F e 3 + + e − = F e 2 + E ∘ = 0.77 V

2 I − = I 2 + 2 e − E ∘ = − 0.54 V

So E c e l l ∘ = 0.77 − 0.54 = 0.23 V

So this reaction is feasible.

Question 2.17 Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

(ii) A g a q + a n d C u ( s )

Answer:

A reaction is feasible only if E c e l l ∘ is positive.

So, anode and cathode reactions will be as follows :-

( A g + + e − = A g ) × 2 E ∘ = 0.80 V

C u = C u + 2 + 2 e − E ∘ = − 0.34 V

and E c e l l ∘ = 0.80 − 0.34 = 0.46 V

So this reaction is feasible.

Question 2.17 Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

(iii) F e a q 3 + a n d B r a q −

Answer:

A reaction is feasible only if E c e l l ∘ is positive.

So, anode and cathode reactions will be as follows :-

( F e + 3 + e − = F e + 2 ) × 2 E ∘ = 0.77 V

2 B r − = B r 2 + 2 e − E ∘ = − 1.09 V

and E c e l l ∘ = 0.77 − 1.09 = − 0.32 V

So this reaction is not feasible.

Question 2.17 Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

(iv) A g s a n d F e a q 3 +

Answer:

A reaction is feasible only if E c e l l ∘ is positive.

So, anode and cathode reactions will be as follows:-

A g = A g + + e − E ∘ = − 0.80 V

F e + 3 + e − = F e + 2 E ∘ = 0.77 V

and E c e l l ∘ = − 0.80 + 0.77 = − 0.03 V

So this reaction is not feasible.

Question 2.17 Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

(v) B r 2 ( a q ) and F e a q 2 +

Answer:

A reaction is feasible only if E c e l l ∘ is positive.

So, anode and cathode reactions will be as follows :-

B r 2 + 2 e − = 2 B r − E ∘ = 1.09 V

F e 2 + = F e 3 + + e − E ∘ = − 0.77 V

and E c e l l ∘ = 1.09 − 0.77 = 0.32 V

So this reaction is feasible.

Question 2.18 Predict the products of electrolysis in each of the following:

(i) An aqueous solution of A g N O 3 with silver electrodes.

Answer:

For the given solution :

At cathode:- Reaction with greater E0 will take place.

A g + + e − = A g ( s )

At anode :-

A g + N O 3 − = A g N O 3 + e −

Hence, silver will get deposited at the cathode, and it will be dissolved at anode.

Question 2.18 Predict the products of electrolysis in each of the following:

(ii) An aqueous solution of A g N O 3 with platinum electrodes.

Answer:

For the given solution :

At cathode :- Reaction with greater E0 will take place.

A g + + e − = A g ( s )

At anode :- Self ionisation will take place due to the presence of water.

H 2 O → 2 H + + 1 2 O 2 + 2 e −

Hence, silver will get deposited at the cathode and O2 will be produced from anode.

Question 2.18 Predict the products of electrolysis in each of the following:

(iii) A dilute solution of H 2 S O 4 with platinum electrodes.

Answer:

For the given solution:

At cathode :- Reaction with a greater E0 will take place.

H + + e − → 1 / 2 H 2

At anode :- Self ionisation of water will take place due to the presence of platinum electrode.

H 2 O → 2 H + + 1 2 O 2 + 2 e −

Hence, H2 gas will be generated at cathode and O2 will be produced from anode.

Question 2.18 Predict the products of electrolysis in each of the following:

(iv) An aqueous solution of C u C I 2 with platinum electrodes.

Answer:

For the given solution :

At cathode :- Reaction with greater E0 will take place.

Cu 2 + + 2 e − → Cu ( s )

At anode :-

2 C l − = C l 2 + 2 e −

Hence, Cu will get deposited at cathode and Cl2 will be produced from anode.

Class 12 Chemistry NCERT Chapter 2: Higher Order Thinking Skill (HOTS) Questions

Enhance your problem-solving abilities with these HOTS questions. They are designed to test analytical thinking and problem-solving ability.

Question: The standard cell potential ( E cell ⊖ ) of a fuel cell based on the oxidation of methanol in air that has been used to power television relay station is measured as 1.21 V . The standard half cell reduction potential for O 2 ( E O 2 / H 2 O 0 ) is 1.229 V.

Choose the correct statement:

(1) The standard half cell reduction potential for the reduction of CO 2 ( E CO 2 / CH 3 OH 0 ) is 19 mV

(2) Oxygen is formed at the anode.

(3) Reactants are fed at one go to each electrode.

(4) Reduction of methanol takes place at the cathode.

Answer:

Fuel cell reaction

CH 3 OH ( I ) + 3 2 O 2 ( g ) → CO 2 ( g ) + 2 H 2 O ( I )
Here O 2 reduces to H 2 O and CH 3 OH oxidises to CO 2 .

Standard cell potential:

E cell ∘ = E cathode ∘ − E anode ∘

Given:

E cell ∘ = 1.21 V E 0 2 / H 2 O ∘ = 1.229 V

Substituting the values,

1.21 = 1.229 − E anode ∘

Solving for E anode ∘ :

E anode ∘ = 1.229 − 1.21 = 0.019 V

0.019 V convert into mV multiply by 1000 = 0.019 * 1000 = 19mV

Hence, the correct answer is option (1).

Question: The molar conductance of an infinitely dilute solution of ammonium chloride was found to be 185 S cm 2 mol − 1 and the ionic conductance of hydroxyl and chloride ions are 170 and 70 S cm 2 mol 1 , respectively. If molar conductance of 0.02 M solution of ammonium hydroxide is 85.5 S cm 2 mol − 1 , its degree of dissociation is given by x × 10 − 1 . The value of x is _______ (Nearest integer)

(1) 3

(2) 2

(3) 4

(4) 1

Answer:

λ m ′ ′ of NH 4 Cl = 185 ( λ m ∘ ) NH 4 + ( λ m ∘ ) Cl − = 185 ( λ m ∘ ) NH 4 = 185 − 70 = 115 Scm 2 mol − 1 ( λ m ∘ ) NH 4 OH = ( λ m ∘ ) NH 4 ∘ + ( λ m ∘ ) OH − = 115 + 170 ( λ m 0 ) NH 4 OH = 285 Scm 2 mol − 1 degree of dissociation = ( λ m ) NH 4 OH ( λ m ∘ ) NH 4 OH = 85.5 285 = 0.3 = 3 × 10 − 1

Hence, the correct answer is option (1).

Question: The standard reduction potential values of some of the p-block ions are given below. Predict the one with the strongest oxidising capacity.

(1) E Sn 4 + / Sn 2 + ⊖ = + 1.15 V

(2) E Tl 3 + / T l ⊖ = + 1.26 V

(3) E Al 3 + / Al ⊖ = − 1.66 V

(4) E Pb 4 + / Pb 2 + ⊖ = + 1.67 V

Answer:

Standard reduction potential value ( + ve ) increases oxidising capacity increases.

From the given options, the higher standard reduction potential is for lead ( Pb ) . ( + 1.67 ) .
so, the p-block ion with strongest oxidizing capacity is Pb (lead).

Hence, the correct answer is option (4).

Approach to Solve Questions of Chapter 2

Electrochemistry is the study of electron movement in an oxidation or reduction reaction at a polarized electrode surface. Here is a more detailed approach on how students can approach solving questions of the NCERT class 12 Electrochemistry:

1. Learn the key Concepts First

Before attempting questions, ensure you're clear on:

  • Redox reactions and balancing
  • Galvanic and Electrolytic Cells

2. Pay special attention to topics like:

  • Electrode potential, standard electrode potential
  • Cell notation and EMF (E°cell)
  • Nernst equation
  • Gibbs free energy and cell potential
  • Conductance and molar conductivity
  • Kohlrausch’s Law
  • Electrolysis and Faraday’s laws
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3. Resources to Use

  • NCERT Textbook & NCERT Exemplar
  • Coaching material or reference books like OP Tandon, Pradeep
  • Previous Year Papers

4. Tips to solve questions

  • Always write units in numericals
  • For EMF, ensure you use the sign of the standard potentials carefully.
  • Practice step-by-step problem solving rather than shortcuts.
  • Make a sheet of formulas for quick revision

Topics of NCERT Class 12 Chemistry Chapter 2

Topics covered in this chapter are given below:

2.1 Electrochemical Cells

2.2 Galvanic Cells

2.2.1 Measurement of Electrode Potential

2.3 Nernst Equation

2.3.1 Equilibrium Constant from Nernst Equation

2.3.2 Electrochemical Cell and Gibbs Energy of the Reaction

2.4 Conductance of Electrolytic Solutions

2.4.1 Measurement of the Conductivity of Ionic Solutions

2.4.2 Variation of Conductivity and Molar Conductivity with Concentration

2.5 Electrolytic Cells and Electrolysis

2.5.1 Products of Electrolysis

2.6 Batteries

2.6.1 Primary Batteries

2.6.2 Secondary Batteries

2.7 Fuel Cells

2.8 Corrosion

Formulas Of NCERT Class 12 Chemistry Electrochemistry

Given below are important formulas from this chapter:

1. Conductance(G) is the reciprocal of resistance (R), and specific conductance or conductivity(k) isthe inverse of resistivity ( ρ )

G = 1 R = 1 ρ ( a l ) k = G ( l a )

2. l/a is called the cell constant of the conductivity cell.

3. Equivalent Conductivity is defined as the conductance of a solution containing 1g of an electrolyte.

Λ e q = K × V

4. Nernst equation

aA+bB → cC+dD

E c e l l = E c e l l o − 0.0591 n l o g [ C ] c [ D ] d [ A ] a [ B ] b

NCERT Exemplar Class 12 Solutions Subject-wise

The hyperlinks of the NCERT exemplar of class 12 are given below:

NCERT Solutions for Class 12 Subject-wise

Below, we have provided hyperlinks to the NCERT solution of class 12. Students can click the respective links and start practising for the exam:

NCERT Books and NCERT Syllabus here:

NCERT books are designed in a way that they prepare students for board examinations and competitive exams as well. Students can refer to the links given below for the NCERT books and Syllabus and start practising for exam:

Frequently Asked Questions (FAQs)

Q: What are NCERT Solutions for Class 12 Chemistry Chapter 2 Electrochemistry
A:

NCERT Solutions for Class 12 Chemistry Chapter 2 are detailed, step-by-step answers to all the questions given in the Electrochemistry chapter of the NCERT textbook. They help students understand key concepts, practise numerical problems, and prepare thoroughly for exams.



Q: Why is electrochemistry important in Class 12 chemistry?
A:

Electrochemistry is important because it explains how chemical reactions produce electrical energy and how electricity can drive chemical changes. It has wide applications in batteries, fuel cells, electroplating, corrosion prevention, and industrial chemical production. 

Q: What is electrochemistry?
A:

Electrochemistry is the branch of chemistry that deals with the interconversion of chemical energy and electrical energy. It involves the study of chemical reactions that occur in electrochemical cells, where oxidation and reduction processes take place. This field finds applications in batteries, fuel cells, and corrosion science.

Q: What is the significance of the standard electrode potential?
A:

The standard electrode potential is a measure of the inherent tendency of a half-cell to be reduced under standard conditions: 1 M concentration, 1 atm pressure, and 25°C. It allows us to predict the direction of spontaneous reactions, determine cell voltages, and compare the reactivity of different electrodes.

Q: What is the concept of conductance and its importance in electrochemistry?
A:

Conductance refers to the ability of a solution to conduct electric current. It is influenced by the concentration of ions present in the solution. In electrochemistry, conductance plays a critical role in determining the efficiency of electrochemical reactions, as higher ionic concentration typically leads to better conductivity and faster reaction rates.

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The date of 12 exam is depends on which board you belongs to . You should check the exact date of your exam by visiting the official website of your respective board.

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Class 12 biology questions papers 2023-2025 are available on cbseacademic.nic.in , and other educational website. You can download PDFs of questions papers with solution for practice. For state boards, visit the official board site or trusted education portal.

Hope this information is useful to you.

Hello Pruthvi,

Taking a drop year to reappear for the Karnataka Common Entrance Test (KCET) is a well-defined process. As a repeater, you are fully eligible to take the exam again to improve your score and secure a better rank for admissions.

The main procedure involves submitting a new application for the KCET through the official Karnataka Examinations Authority (KEA) website when registrations open for the next academic session. You must pay the required application fee and complete all formalities just like any other candidate. A significant advantage for you is that you do not need to retake your 12th board exams. Your previously secured board marks in the qualifying subjects will be used again. Your new KCET rank will be calculated by combining these existing board marks with your new score from the KCET exam. Therefore, your entire focus during this year should be on preparing thoroughly for the KCET to achieve a higher score.

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Yes, you can switch from Science in Karnataka State Board to Commerce in CBSE for 12th. You will need a Transfer Certificate from your current school and meet the CBSE school’s admission requirements. Since you haven’t studied Commerce subjects like Accountancy, Economics, and Business Studies, you may need to catch up before or during 12th. Not all CBSE schools accept direct admission to 12th from another board, so some may ask you to join Class 11 first. Make sure to check the school’s rules and plan your subject preparation.



Hello

For the 12th CBSE Hindi Medium board exam, important questions usually come from core chapters like “Madhushala”, “Jhansi ki Rani”, and “Bharat ki Khoj”.
Questions often include essay writing, letter writing, and comprehension passages. Grammar topics like Tenses, Voice Change, and Direct-Indirect Speech are frequently asked.
Students should practice poetry questions on themes and meanings. Important questions also cover summary writing and translation from Hindi to English or vice versa.
Previous years’ question papers help identify commonly asked questions.
Focus on writing practice to improve handwriting and presentation. Time management during exams is key to answering all questions effectively.