List of top Chemistry Questions on Electrochemistry asked in COMEDK UGET

Which of the following statements is correct?
Resistance of 2 M solution of an electrolyte is $50\text{ }\Omega$. The conductivity of the solution is $3\text{ S m}^{-1}$. If the resistance of 4 M solution of the same electrolyte is $260\text{ }\Omega$, its molar conductivity is:
The quantity of $\text{Ca}$ that can be produced from molten $\text{CaCl}_2$, with the same quantity of electricity (in coulombs) required to produce $8\text{ g}$ of $\text{Mg}$ from molten $\text{MgCl}_2$ is: [Atomic mass of $\text{Mg} = 24\text{ u}$; Atomic mass of $\text{Ca} = 40\text{ u}$]}
When \( 0.1 \, mol \, L^{-1} \) of KCl was filled in a Conductivity cell the resistance was 80 ohms at 298 K. Conductivity of \( 0.1 \, M \) KCl at 298 K is \( 1.29 \, S \, m^{-1} \). The same cell when filled with an unknown electrolyte of concentration \( 0.025 \, M \), had a resistance of 92 ohms. What is the Molar conductivity of the electrolyte at the given concentration?
Two statements, one Assertion and the other Reason, are given. Choose the correct option.
Assertion: During the electrolysis of aqueous NaCl, \( Cl_2 \) is liberated at the anode in preference to \( O_2 \) and water gets reduced to \( H_2 \) at cathode.
Reason: The reaction at anode with lower oxidation potential is not preferred due to over potential of oxygen.
Two statements, one Assertion and the other Reason are given. Choose the correct option. Assertion: For strong electrolytes, the plot of Molar conductivity versus Concentration gives a straight line with slope equal to +A and intercept equal to \( \lambda_m \).
Reason: For strong electrolytes, \( \lambda_m \) increases slowly with dilution due to an increase in the distance between the ions and increase in ionic mobility.

The standard reduction potential at 25°C for \( MnO_4^- / H^+ \) is \( +1.49 \, \text{V} \).

The given standard reduction potentials are:

  • \( Co^{3+}/Co^{2+} = +1.81 \, \text{V} \)
  • \( Cr^{3+}/Cr = -0.74 \, \text{V} \)
  • \( Au^{3+}/Au = +1.50 \, \text{V} \)
  • \( Ag^+/Ag = +0.80 \, \text{V} \)

We need to identify which species cannot be oxidized by \( MnO_4^- / H^+ \).

Concept: A species will be oxidized by \( MnO_4^- \) only if its reduction potential is less than \( +1.49 \, \text{V} \).

Thus, species with higher reduction potential than \( MnO_4^- \) cannot be oxidized.

Comparing values:

  • \( Co^{3+}/Co^{2+} = +1.81 \, \text{V} \) → cannot be oxidized
  • \( Au^{3+}/Au = +1.50 \, \text{V} \) → cannot be oxidized

Final Answer: \( Co^{3+}/Co^{2+} \) and \( Au^{3+}/Au \)

A current of 1.5 A is passed for 2 hours through an aqueous solution of PdX\(_n\), where X is a monovalent anion. During the electrolysis process 2.977 g of Palladium metal gets deposited at the cathode. Calculate the charge on Pd ions. (Atomic mass of Pd = 106.4 g/mol).