NEET Electrochemistry — Set 17

Question 1

In a lead storage battery during charging, what is the anode reaction?

Accepted Answer

Charging reverses discharge: Anode: $ PbSO_4 + 2H_2O \rightarrow PbO_2 + SO_4^{2-} + 4H^+ + 2e^- $.

Question 2

A dry cell delivers 0.1 A for 19300 s. What mass of MnO$_2$ (molar mass 87 g/mol) is reduced at the cathode? (F = 96500 C/mol)

Accepted Answer

Charge = $ 0.1 \times 19300 = 1930 \, C $. Cathode: $ MnO_2 + H^+ + e^- \rightarrow MnO(OH) $, 1 mol MnO$_2$ requires 1F. Faradays = $ \frac{1930}{96500} = 0.02 \, F $, Moles = $ 0.02 \, mol $, Mass = $ 0.02 \times 87 = 1.74 \, g $.

Question 3

In a mercury cell, what is the reducing agent?

Accepted Answer

Reaction: $ Zn(Hg) + HgO(s) \rightarrow ZnO(s) + Hg(l) $. Zn is oxidized, so it’s the reducing agent.

NEET Chemistry: Electrochemistry — Practice Set 17

Q1. In a lead storage battery during charging, what is the anode reaction?

Q2. A dry cell delivers 0.1 A for 19300 s. What mass of MnO\(_2\) (molar mass 87 g/mol) is reduced at the cathode? (F = 96500 C/mol)

Q3. In a mercury cell, what is the reducing agent?

Q4. How many coulombs are required to deposit 5.4 g of aluminum from an AlCl\(_3\) solution? (Atomic mass of Al = 27 g/mol, F = 96500 C/mol)

Q5. In a dry cell, 0.435 g of MnO\(_2\) (molar mass 87 g/mol) is reduced to MnO(OH). How many coulombs are consumed? (F = 96500 C/mol)

Q6. What is the cell potential at 298 K for \( Zn(s) | Zn^{2+}(0.01 \, M) || Cu^{2+}(0.1 \, M) | Cu(s) \)? (Given: \( E^\circ_{cell} = 1.10 \, V \))

Q7. The conductivity of a 0.01 M LiNO\(_3\) solution is 0.00135 S cm\(^{-1}\). What is the molar conductivity?

Q8. What is the cell constant of a conductivity cell if the resistance of a 0.01 M KCl solution is 200 Ω and its conductivity is 0.00141 S cm\(^{-1}\)?

Q9. A conductivity cell with cell constant 0.6 cm\(^{-1}\) shows a resistance of 200 Ω with a 0.03 M KCl solution. What is the molar conductivity?

Q10. In the electrolysis of aqueous CuCl\(_2\) with inert electrodes, what is the product at the cathode?