How many electrons are involved in the reduction of 1 mole of \( ClO_4^- \) to \( Cl^- \) in acidic medium?

\( ClO_4^- + 8H^+ + 8e^- \rightarrow Cl^- + 4H_2O \). 8 electrons per mole.

A hydrogen electrode operates at 298 K with \( P_{H_2} = 1.5 \, atm \) and \( [H^+] = 0.0001 \, M \). What is its potential? (Given: \( E^\circ_{H^+/H_2} = 0.00 \, V \))

\( E = E^\circ - \frac{0.059}{2} \log \frac{P_{H_2}}{[H^+]^2} \). \( E = 0 - 0.0295 \log \frac{1.5}{10^{-8}} = 0 - 0.0295 \times 8.176 = -0.2412 \, V \).

NEET Chemistry: Electrochemistry — Practice Set 15 (10 MCQs)

Chemistry — Electrochemistry

Set 15 of 20

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In a fuel cell with H\(_2\) and O\(_2\), what is the cathode reaction?

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NEET Chemistry: Electrochemistry — Practice Set 15

Q1. In a fuel cell with H\(_2\) and O\(_2\), what is the cathode reaction?

Q2. How many electrons are involved in the reduction of 1 mole of \( ClO_4^- \) to \( Cl^- \) in acidic medium?

Q3. A hydrogen electrode operates at 298 K with \( P_{H_2} = 1.5 \, atm \) and \( [H^+] = 0.0001 \, M \). What is its potential? (Given: \( E^\circ_{H^+/H_2} = 0.00 \, V \))

Q4. The standard emf of a cell is 0.96 V, and its equilibrium constant at 298 K is \( 10^{32} \). How many electrons are transferred in the cell reaction?

Q5. What is the emf of the cell \( Cr(s) | Cr^{3+}(0.001 \, M) || Cu^{2+}(0.01 \, M) | Cu(s) \) at 298 K? (Given: \( E^\circ_{Cr^{3+}/Cr} = -0.74 \, V \), \( E^\circ_{Cu^{2+}/Cu} = 0.34 \, V \))

Q6. The molar conductivity of RbCl at infinite dilution is 152.7 S cm\(^2\) mol\(^{-1}\). If \( \lambda^\circ_{Rb^+} = 77.8 \, S \, cm^2 \, mol^{-1} \), what is \( \lambda^\circ_{Cl^-} \)?

Q7. The degree of dissociation of a weak acid is 0.02, and its molar conductivity at infinite dilution is 400 S cm\(^2\) mol\(^{-1}\). What is its molar conductivity at that concentration?

Q8. The dissociation constant of acetic acid is 1.78 × 10\(^{-5}\) mol L\(^{-1}\) at 0.001 M concentration with molar conductivity 48.15 S cm\(^2\) mol\(^{-1}\). What is its \( \Lambda_m^\circ \)?

Q9. A weak acid has \( \Lambda_m^\circ = 380 \, S \, cm^2 \, mol^{-1} \) and \( \Lambda_m = 19 \, S \, cm^2 \, mol^{-1} \) at 0.02 M. What is the dissociation constant \( K_a \)?

Q10. A cell has \( E^\circ_{cell} = 1.10 \, V \) and \( \Delta_r G^\circ = -424600 \, J/mol \) at 298 K. What is the number of electrons transferred? (F = 96500 C/mol)