NEET Electrochemistry — Set 9

Question 1

A dry cell delivers 0.25 A for 9650 s. How many grams of zinc are oxidized at the anode? (Atomic mass of Zn = 65 g/mol, F = 96500 C/mol)

Accepted Answer

Charge = $ 0.25 \times 9650 = 2412.5 \, C $. $ Zn \rightarrow Zn^{2+} + 2e^- $, 1 mol Zn (65 g) requires 2F. Faradays = $ \frac{2412.5}{96500} = 0.025 \, F $, Moles = $ \frac{0.025}{2} = 0.0125 \, mol $, Mass = $ 0.0125 \times 65 = 0.8125 \, g $.

Question 2

What is the degree of dissociation of a weak electrolyte with $ \Lambda_m = 46 \, S \, cm^2 \, mol^{-1} $ and $ \Lambda_m^\circ = 404 \, S \, cm^2 \, mol^{-1} $?

Accepted Answer

$ \alpha = \frac{\Lambda_m}{\Lambda_m^\circ} = \frac{46}{404} = 0.114 $.

Question 3

What is the cell potential at 298 K for $ Cu(s) | Cu^{2+}(0.01 \, M) || Ag^+(0.1 \, M) | Ag(s) $? (Given: $ E^\circ_{Cu^{2+}/Cu} = 0.34 \, V $, $ E^\circ_{Ag^+/Ag} = 0.80 \, V $)

Accepted Answer

$ E^\circ_{cell} = 0.80 - 0.34 = 0.46 \, V $. $ E_{cell} = 0.46 - \frac{0.059}{2} \log \frac{0.01}{0.1^2} = 0.46 + 0.0295 = 0.4895 \, V $.

NEET Chemistry: Electrochemistry — Practice Set 9

Q1. A dry cell delivers 0.25 A for 9650 s. How many grams of zinc are oxidized at the anode? (Atomic mass of Zn = 65 g/mol, F = 96500 C/mol)

Q2. What is the degree of dissociation of a weak electrolyte with \( \Lambda_m = 46 \, S \, cm^2 \, mol^{-1} \) and \( \Lambda_m^\circ = 404 \, S \, cm^2 \, mol^{-1} \)?

Q3. What is the cell potential at 298 K for \( Cu(s) | Cu^{2+}(0.01 \, M) || Ag^+(0.1 \, M) | Ag(s) \)? (Given: \( E^\circ_{Cu^{2+}/Cu} = 0.34 \, V \), \( E^\circ_{Ag^+/Ag} = 0.80 \, V \))

Q4. What is the approximate cell potential of a mercury cell?

Q5. A fuel cell produces 0.448 L of H\(_2\)O vapor (STP) at the cathode from O\(_2\). How many coulombs are involved? (F = 96500 C/mol)

Q6. In a lead storage battery during discharge, 0.1515 g of PbSO\(_4\) (molar mass 303 g/mol) is formed at the anode. How many coulombs are involved? (F = 96500 C/mol)

Q7. The molar conductivity of a 0.1 M KCl solution is 129 S cm\(^2\) mol\(^{-1}\). If the conductivity of the solution is 0.0129 S cm\(^{-1}\), what is the concentration used in the calculation?

Q8. What is the equilibrium constant for a cell reaction with \( E^\circ_{cell} = 0.118 \, V \) at 298 K involving 1 electron?

Q9. In a dry cell, what is the electrolyte paste made of?

Q10. What is the equilibrium constant for a cell reaction with \( E^\circ_{cell} = 0.295 \, V \) at 298 K involving 1 electron?