NEET Electrochemistry — Set 2

Question 1

In a lead storage battery, what is the electrolyte?

Accepted Answer

The electrolyte in a lead storage battery is dilute sulfuric acid (H$_2$SO$_4$).

Question 2

A weak acid has $ \Lambda_m^\circ = 350 \, S \, cm^2 \, mol^{-1} $ and $ \Lambda_m = 17.5 \, S \, cm^2 \, mol^{-1} $ at 0.05 M. What is the dissociation constant $ K_a $?

Accepted Answer

$ \alpha = \frac{\Lambda_m}{\Lambda_m^\circ} = \frac{17.5}{350} = 0.05 $. $ K_a = \frac{\alpha^2 c}{1 - \alpha} = \frac{0.05^2 \times 0.05}{1 - 0.05} = \frac{0.0025 \times 0.05}{0.95} = 1.316 \times 10^{-4} $.

Question 3

How many electrons are involved in the reduction of 1 mole of $ MnO_4^- $ to $ MnO_2 $ in basic medium?

Accepted Answer

$ MnO_4^- + 2H_2O + 3e^- \rightarrow MnO_2 + 4OH^- $. 3 electrons per mole.

NEET Chemistry: Electrochemistry — Practice Set 2

Q1. In a lead storage battery, what is the electrolyte?

Q2. A weak acid has \( \Lambda_m^\circ = 350 \, S \, cm^2 \, mol^{-1} \) and \( \Lambda_m = 17.5 \, S \, cm^2 \, mol^{-1} \) at 0.05 M. What is the dissociation constant \( K_a \)?

Q3. How many electrons are involved in the reduction of 1 mole of \( MnO_4^- \) to \( MnO_2 \) in basic medium?

Q4. A lead storage battery delivers 1.5 A for 10 hours during discharge. How many grams of PbSO\(_4\) (molar mass 303 g/mol) are formed at the anode? (F = 96500 C/mol)

Q5. What is the emf of the cell \( Mn(s) | Mn^{2+}(0.05 \, M) || H^+(0.005 \, M) | H_2(g)(1 \, bar) | Pt(s) \) at 298 K? (Given: \( E^\circ_{Mn^{2+}/Mn} = -1.18 \, V \), \( E^\circ_{H^+/H_2} = 0.00 \, V \))

Q6. A lead storage battery delivers 1 A for 4825 s. What is the mass of PbSO\(_4\) (molar mass 303 g/mol) formed at the cathode? (F = 96500 C/mol)

Q7. A cell reaction has \( \Delta_r G^\circ = -212300 \, J/mol \) and involves 2 electrons at 298 K. What is the equilibrium constant?

Q8. During electrolysis of aqueous NaI with inert electrodes, 0.224 L of H\(_2\) (STP) is produced at the cathode. How many coulombs were passed? (F = 96500 C/mol)

Q9. A hydrogen electrode operates at 298 K with \( P_{H_2} = 0.1 \, atm \) and pH = 4. What is its potential? (Given: \( E^\circ_{H^+/H_2} = 0.00 \, V \))

Q10. The resistance of a conductivity cell with 0.001 M KCl solution is 1500 Ω, and its conductivity is 0.146 × 10\(^{-3}\) S cm\(^{-1}\). What is the cell constant?