NEET Electrochemistry — Set 5

Question 1

What is the potential of a hydrogen electrode in a solution with $ [H^+] = 10^{-5} \, M $ 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^{-5} $, $ n = 1 $. $ E = 0 - 0.059 \times 5 = -0.295 \, V $.

Question 2

How many coulombs are required to deposit 0.965 g of barium from a BaCl$_2$ solution? (Atomic mass of Ba = 137 g/mol, F = 96500 C/mol)

Accepted Answer

$ Ba^{2+} + 2e^- \rightarrow Ba $. 1 mol Ba (137 g) requires 2F. Moles = $ \frac{0.965}{137} = 0.00704 \, mol $, Charge = $ 0.00704 \times 2 \times 96500 = 1358.24 \, C $.

Question 3

In a dry cell, the cathode reaction produces MnO(OH). If 0.87 g of MnO$_2$ (atomic mass Mn = 55, O = 16) is reduced, how many coulombs are consumed? (F = 96500 C/mol)

Accepted Answer

$ MnO_2 + H^+ + e^- \rightarrow MnO(OH) $. Molar mass = $ 55 + 32 = 87 \, g/mol $. Moles = $ \frac{0.87}{87} = 0.01 \, mol $, Charge = $ 0.01 \times 96500 = 965 \, C $.

NEET Chemistry: Electrochemistry — Practice Set 5

Q1. What is the potential of a hydrogen electrode in a solution with \( [H^+] = 10^{-5} \, M \) at 298 K? (Given: \( E^\circ_{H^+/H_2} = 0.00 \, V \))

Q2. How many coulombs are required to deposit 0.965 g of barium from a BaCl\(_2\) solution? (Atomic mass of Ba = 137 g/mol, F = 96500 C/mol)

Q3. In a dry cell, the cathode reaction produces MnO(OH). If 0.87 g of MnO\(_2\) (atomic mass Mn = 55, O = 16) is reduced, how many coulombs are consumed? (F = 96500 C/mol)

Q4. How many Faradays are required to reduce 1 mole of \( Cu^{2+} \) to \( Cu^+ \)?

Q5. What is the emf of a cell \( Fe(s) | Fe^{2+}(0.1 \, M) || H^+(0.001 \, M) | H_2(g)(1 \, bar) | Pt(s) \) at 298 K? (Given: \( E^\circ_{Fe^{2+}/Fe} = -0.44 \, V \), \( E^\circ_{H^+/H_2} = 0.00 \, V \))

Q6. How many electrons are transferred in the reduction of 1 mole of \( NO_3^- \) to \( NH_4^+ \) in acidic medium?

Q7. A hydrogen electrode in a solution with \( P_{H_2} = 2 \, atm \) and \( [H^+] = 0.002 \, M \) operates at 298 K. What is its potential? (Given: \( E^\circ_{H^+/H_2} = 0.00 \, V \))

Q8. What is the emf of the cell \( Sn(s) | Sn^{2+}(0.002 \, M) || Pb^{2+}(0.02 \, M) | Pb(s) \) at 298 K? (Given: \( E^\circ_{Sn^{2+}/Sn} = -0.14 \, V \), \( E^\circ_{Pb^{2+}/Pb} = -0.13 \, V \))

Q9. In a dry cell, what is the approximate cell potential?

Q10. A cell \( Fe(s) | Fe^{2+}(0.02 \, M) || I_2(s) | I^-(0.1 \, M) | Pt(s) \) operates at 298 K. What is the cell potential? (Given: \( E^\circ_{Fe^{2+}/Fe} = -0.44 \, V \), \( E^\circ_{I_2/I^-} = 0.54 \, V \))