NEET Electrochemistry — Set 8

Question 1

What is the potential of a hydrogen electrode in a solution with pH = 2 at 298 K? (Given: $ E^\circ_{H^+/H_2} = 0.00 \, V $)

Accepted Answer

$ E = E^\circ - \frac{0.059}{n} \log \frac{1}{[H^+]} $, $ [H^+] = 10^{-2} $, $ n = 1 $. $ E = 0 - 0.059 \times 2 = -0.118 \, V $.

Question 2

How many electrons are involved in the reduction of 1 mole of $ Fe^{3+} $ to $ Fe $?

Accepted Answer

$ Fe^{3+} + 3e^- \rightarrow Fe $. 3 electrons are required per mole.

Question 3

What is the emf of a cell $ Cd(s) | Cd^{2+}(0.1 \, M) || Ag^+(0.001 \, M) | Ag(s) $ at 298 K? (Given: $ E^\circ_{Cd^{2+}/Cd} = -0.40 \, V $, $ E^\circ_{Ag^+/Ag} = 0.80 \, V $)

Accepted Answer

$ E^\circ_{cell} = 0.80 - (-0.40) = 1.20 \, V $. $ E_{cell} = 1.20 - \frac{0.059}{2} \log \frac{0.1}{0.001} = 1.20 - 0.059 = 1.141 \, V $.

NEET Chemistry: Electrochemistry — Practice Set 8

Q1. What is the potential of a hydrogen electrode in a solution with pH = 2 at 298 K? (Given: \( E^\circ_{H^+/H_2} = 0.00 \, V \))

Q2. How many electrons are involved in the reduction of 1 mole of \( Fe^{3+} \) to \( Fe \)?

Q3. What is the emf of a cell \( Cd(s) | Cd^{2+}(0.1 \, M) || Ag^+(0.001 \, M) | Ag(s) \) at 298 K? (Given: \( E^\circ_{Cd^{2+}/Cd} = -0.40 \, V \), \( E^\circ_{Ag^+/Ag} = 0.80 \, V \))

Q4. What is the standard emf of a cell with the reaction \( Pb(s) + Hg_2^{2+}(aq) \rightarrow Pb^{2+}(aq) + 2Hg(l) \)? (Given: \( E^\circ_{Pb^{2+}/Pb} = -0.13 \, V \), \( E^\circ_{Hg_2^{2+}/Hg} = 0.79 \, V \))

Q5. A cell \( Cu(s) | Cu^{2+}(0.01 \, M) || Cl_2(g)(0.5 \, atm) | Cl^-(0.05 \, M) | Pt(s) \) operates at 298 K. What is the cell potential? (Given: \( E^\circ_{Cu^{2+}/Cu} = 0.34 \, V \), \( E^\circ_{Cl_2/Cl^-} = 1.36 \, V \))

Q6. How many coulombs are required to reduce 1 mole of \( Br_2 \) to \( Br^- \)? (F = 96500 C/mol)

Q7. In a lead storage battery during discharge, what is the total change in oxidation state of lead from reactants to products at both electrodes?

Q8. In a lead storage battery during charging, what is the oxidation state of lead in the anode product?

Q9. What is the emf of the cell \( Pb(s) | Pb^{2+}(0.005 \, M) || Ag^+(0.05 \, M) | Ag(s) \) at 298 K? (Given: \( E^\circ_{Pb^{2+}/Pb} = -0.13 \, V \), \( E^\circ_{Ag^+/Ag} = 0.80 \, V \))

Q10. How many coulombs are required to reduce 1 mole of \( MnO_4^- \) to \( Mn^{2+} \) in acidic medium? (Faraday constant = 96500 C/mol)