Electrochemistry is a high-scoring chapter in Class 12 Chemistry because it connects redox reactions with measurable electrical quantities (cell emf, electrode potentials), and also explains real processes like corrosion and electroplating. In board and competitive exams, questions commonly test Nernst equation, equilibrium/thermodynamics links (, ), concentration effects, and Faraday’s laws—so mastering core concepts and careful option-based calculations is essential.
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Marking
Q1. A concentration cell at is constructed as . Using the Nernst equation , the emf of the cell is:
Q2. At a galvanic cell is: . Given and , calculate the initial cell emf using .
Q3. A solution of acetic acid at has molar conductivity . Given limiting ionic molar conductivities and , calculate the degree of dissociation using and .
Q4. A concentration cell at uses two silver electrodes. Initially both compartments have . To one compartment Cl is added and AgCl(s) precipitates. Given and with , the emf of the cell (assume the compartment without Cl is the cathode) is approximately:
Q5. A silver electrode is immersed in a solution with total silver and (assume remains effectively constant). The complex [\text{Ag(NH}_3)_2}]^+ forms with . Given at , and using the relations and , the electrode potential is closest to:
Q6. A concentration cell is constructed with copper electrodes: at . What is the emf of the cell?
Q7. Consider the galvanic cell at . Given and , what is the emf of the cell?
Q8. For the redox reaction
at , the standard reduction potentials are and . What is the equilibrium constant for this reaction?
Q9. For the cell reaction
the standard enthalpy and entropy changes are and . Assuming and are temperature independent, at what temperature will the standard emf of the cell become zero?
Q10. Consider the cell written as where the right-hand half-cell is in pure water saturated with . Given at and using for , what is the emf for the cell as written (left to right)?
Q11. A current of is passed through an aqueous solution of for . Assuming current efficiency and that the cathodic reaction is , what mass of copper (in grams) is deposited at the cathode? (Take and )
Q12. At a galvanic cell is constructed with the following half-cells: and . Given and , determine the cell emf and identify the anode. Use the Nernst equation .
Anode:
Anode:
Anode:
Anode:
Q13. Two half-cells of a concentration cell are made using silver electrodes; each compartment has volume . The left compartment initially contains and the right . When the cell is allowed to run until concentrations become equal (volume change negligible), how many moles of Ag are deposited on the cathode?
Q14. Assertion (A): In the electrolysis of concentrated using inert electrodes, chlorine gas is produced at the anode instead of oxygen even though is lower than .
Reason (R): Chlorine formed at the anode hydrolyses with water producing hypochlorous acid and chloride, e.g.
Both A and R are true and R explains A.
Both A and R are true but R does not explain A.
A is true but R is false.
A is false but R is true.
Q15. A cell is made from a copper electrode in and a hydrogen electrode in contact with at in a solution of pH at . Given and the Nernst equation , calculate the cell emf and identify the cathode.
Cathode: electrode
Cathode: electrode
Cathode: electrode
Cathode: electrode
...and 5 more challenging questions available in the interactive simulator.