Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because
- zinc is lighter than iron
- zinc has lower melting point than iron
- zinc has lower negative electrode potential than iron
- zinc has higher negative electrode potential than iron
The Correct Option is D
Solution and Explanation
Electrochemical Series and Corrosion Protection
The standard reduction potentials for zinc and iron are given as:
\(E^{0}_{\text{Zn}^{2+}/\text{Zn}} = - 0.76 \, \text{V}\)
\(E^{0}_{\text{Fe}^{2+}/\text{Fe}} = - 0.76 \, \text{V}\)
Explanation:
Both zinc and iron have the same standard reduction potential of -0.76 V. However, zinc has a higher negative standard reduction potential (SRP), which means that zinc is more readily oxidized than iron. Therefore, in an electrochemical cell or corrosion process:
- Zinc (Zn) acts as the anode where it gets oxidized to zinc ions (\( \text{Zn}^{2+} \)) and loses electrons.
- Iron (Fe) acts as the cathode, where the electrons from zinc are accepted, and iron is protected from corrosion.
Thus, zinc protects iron by sacrificially oxidizing itself, making it a useful material for galvanizing or protecting iron surfaces from rusting.
Top Questions on Electrochemistry
- Calculate \( E_{\text{cell}} \) of a galvanic cell in which the following reaction takes place at 25°C:
\[ \text{Zn(s)} + \text{Pb}^{2+}(0.02M) \longrightarrow \text{Zn}^{2+}(0.1M) + \text{Pb(s)} \quad \text{[Given: } E^0_{\text{Zn}^{2+}/\text{Zn}} = -0.76V, \; E^0_{\text{Pb}^{2+}/\text{Pb}} = -0.13V, \; \log 2 = 0.3010, \; \log 4 = 0.6021, \; \log 5 = 0.6990 \text{]} \]- CBSE CLASS XII - 2025
- Chemistry
- Electrochemistry
- What is the standard electrode potential of a half-reaction in which electrons are transferred from \(Ag^+\) to \(Ag\)?
- VITEEE - 2025
- Chemistry
- Electrochemistry
- The standard electrode potential for $\text{Zn}^{2+}/\text{Zn}$ is $-0.76$ V and for $\text{Cu}^{2+}/\text{Cu}$ is $+0.34$ V. The EMF of the cell
$$ \text{Zn}|\text{Zn}^{2+}||\text{Cu}^{2+}|\text{Cu} $$ is:- BITSAT - 2025
- Chemistry
- Electrochemistry
- The standard reduction potentials are: \[ \mathrm{Cu^{2+} + 2e^- \rightarrow Cu} \quad E^\circ = +0.34\,V \] \[ \mathrm{Zn^{2+} + 2e^- \rightarrow Zn} \quad E^\circ = -0.76\,V \] Calculate the standard cell potential for the reaction: \[ \mathrm{Zn + Cu^{2+} \rightarrow Zn^{2+} + Cu} \]
- BITSAT - 2025
- Chemistry
- Electrochemistry
- In the electrolysis of molten \( \mathrm{NaCl} \), what is produced at the cathode?
- BITSAT - 2025
- Chemistry
- Electrochemistry
Questions Asked in NEET exam
- Which of the following organisms cannot fix nitrogen? A. Azotobacter
B. Oscillatoria
C. Anabaena
D. Volvox
E. Nostoc
Choose the correct answer from the options given below:- NEET (UG) - 2025
- Nitrogen Fixation
- Which of the following are paramagnetic?
A. [NiCl$_4$]$^{2-}$
B. Ni(CO)$_4$
C. [Ni(CN)$_4$]$^{2-}$
D. [Ni(H$_2$O)$_6$]$^{2+}$
E. Ni(PPh$_3$)$_4$
Choose the correct answer from the options given below:- NEET (UG) - 2025
- Coordination chemistry
Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): A typical unfertilized, angiosperm embryo sac at maturity is 8-nucleate and 7-celled.
Reason (R): The egg apparatus has 2 polar nuclei.In the light of the above statements, choose the correct answer from the options given below:
- NEET (UG) - 2025
- Angiosperms
- A ball of mass 0.5 kg is dropped from a height of 10 m. The ball hits the ground and rises to a height of 1.5 m. The impulse imparted to the ball during its collision with the ground is : (Take \(g = 9.8 \, \text{m/s}^2\))
- NEET (UG) - 2025
- Collision and Impulse
- Consider the diameter of a spherical object being measured with the help of a Vernier Callipers. Suppose its 10 Vernier Scale Divisions (V.S.D.) are equal to its 9 Main Scale Divisions (M.S.D.). The least count in the M.S. is 0.1 cm and the zero of V.S. is at -0.1 cm when the jaws of Vernier callipers are closed. If the main scale reading for the diameter is \(M = 5\) cm and the number of coinciding vernier division is 8, the measured diameter after zero error correction, is:
- NEET (UG) - 2025
- Measurement of length
Concepts Used:
Electrochemical Cells
An electrochemical cell is a device that is used to create electrical energy through the chemical reactions which are involved in it. The electrical energy supplied to electrochemical cells is used to smooth the chemical reactions. In the electrochemical cell, the involved devices have the ability to convert the chemical energy to electrical energy or vice-versa.
Classification of Electrochemical Cell:
Cathode
- Denoted by a positive sign since electrons are consumed here
- A reduction reaction occurs in the cathode of an electrochemical cell
- Electrons move into the cathode
Anode
- Denoted by a negative sign since electrons are liberated here
- An oxidation reaction occurs here
- Electrons move out of the anode
Types of Electrochemical Cells:
Galvanic cells (also known as Voltaic cells)
- Chemical energy is transformed into electrical energy.
- The redox reactions are spontaneous in nature.
- The anode is negatively charged and the cathode is positively charged.
- The electrons originate from the species that undergo oxidation.
Electrolytic cells
- Electrical energy is transformed into chemical energy.
- The redox reactions are non-spontaneous.
- These cells are positively charged anode and negatively charged cathode.
- Electrons originate from an external source.