NEET Electrochemistry — Set 20

Question 1

What is the limiting molar conductivity of CaCl$_2$ in water at 298 K, given $ \lambda^\circ_{Ca^{2+}} = 119 \, S \, cm^2 \, mol^{-1} $, $ \lambda^\circ_{Cl^-} = 76.3 \, S \, cm^2 \, mol^{-1} $?

Accepted Answer

$ \Lambda_m^\circ = \lambda^\circ_{Ca^{2+}} + 2 \lambda^\circ_{Cl^-} = 119 + 2 \times 76.3 = 271.6 \, S \, cm^2 \, mol^{-1} $.

Question 2

In a fuel cell, what is the cathode reaction?

Accepted Answer

Cathode: $ O_2 + 4H^+ + 4e^- \rightarrow 2H_2O $.

Question 3

What is the emf of a cell $ Zn(s) | Zn^{2+}(0.001 \, M) || H^+(1 \, M) | H_2(g)(1 \, bar) | Pt(s) $ at 298 K? (Given: $ E^\circ_{Zn^{2+}/Zn} = -0.76 \, V $, $ E^\circ_{H^+/H_2} = 0.00 \, V $)

Accepted Answer

$ E^\circ_{cell} = 0.00 - (-0.76) = 0.76 \, V $. $ E_{cell} = 0.76 - \frac{0.059}{2} \log \frac{0.001}{1^2} = 0.76 + 0.0885 = 0.8485 \, V $.

NEET Chemistry: Electrochemistry — Practice Set 20

Q1. What is the limiting molar conductivity of CaCl\(_2\) in water at 298 K, given \( \lambda^\circ_{Ca^{2+}} = 119 \, S \, cm^2 \, mol^{-1} \), \( \lambda^\circ_{Cl^-} = 76.3 \, S \, cm^2 \, mol^{-1} \)?

Q2. In a fuel cell, what is the cathode reaction?

Q3. What is the emf of a cell \( Zn(s) | Zn^{2+}(0.001 \, M) || H^+(1 \, M) | H_2(g)(1 \, bar) | Pt(s) \) at 298 K? (Given: \( E^\circ_{Zn^{2+}/Zn} = -0.76 \, V \), \( E^\circ_{H^+/H_2} = 0.00 \, V \))

Q4. In the electrolysis of aqueous K\(_2\)SO\(_4\) with inert electrodes, what gas is produced at the anode?

Q5. A cell operates with \( E_{cell} = 1.50 \, V \) at 298 K when \( [Anode] = 0.001 \, M \) and \( [Cathode] = 0.1 \, M \). If \( E^\circ_{cell} = 1.44 \, V \), what is the reaction quotient \( Q \)?

Q6. In a dry cell, what is the oxidation state of manganese in the cathode product MnO(OH)?

Q7. How much time (in seconds) is required to deposit 0.635 g of copper from CuSO\(_4\) solution using a current of 0.5 A? (Atomic mass of Cu = 63.5 g/mol, F = 96500 C/mol)

Q8. The resistance of a conductivity cell with 0.02 M NaCl solution is 500 Ω, and its conductivity is 0.0024 S cm\(^{-1}\). What is the cell constant?

Q9. The molar conductivity of a strong electrolyte at infinite dilution is 240 S cm\(^2\) mol\(^{-1}\). If its molar conductivity at 0.01 M is 228 S cm\(^2\) mol\(^{-1}\), what is the degree of dissociation at this concentration?

Q10. The degree of dissociation of a weak electrolyte is 0.05, and its molar conductivity is 19 S cm\(^2\) mol\(^{-1}\). What is its \( \Lambda_m^\circ \)?