NEET Electrochemistry — Set 13

Question 1

The molar conductivity of a 0.005 M solution is 80 S cm$^2$ mol$^{-1}$. What is the conductivity of the solution?

Accepted Answer

$ \Lambda_m = \frac{\kappa \times 1000}{c} $, $ 80 = \frac{\kappa \times 1000}{0.005} $, $ \kappa = 0.0004 \, S \, cm^{-1} $.

Question 2

What is the emf of the cell $ Mn(s) | Mn^{2+}(0.005 \, M) || Hg^{2+}(0.02 \, M) | Hg(l) $ at 298 K? (Given: $ E^\circ_{Mn^{2+}/Mn} = -1.18 \, V $, $ E^\circ_{Hg^{2+}/Hg} = 0.85 \, V $)

Accepted Answer

$ E^\circ_{cell} = 0.85 - (-1.18) = 2.03 \, V $. $ E_{cell} = 2.03 - \frac{0.059}{2} \log \frac{0.005}{0.02} = 2.03 + 0.02065 = 2.05065 \, V $.

Question 3

What is the standard emf of a cell with the reaction $ Cr(s) + 3Ag^+(aq) \rightarrow Cr^{3+}(aq) + 3Ag(s) $? (Given: $ E^\circ_{Cr^{3+}/Cr} = -0.74 \, V $, $ E^\circ_{Ag^+/Ag} = 0.80 \, V $)

Accepted Answer

$ E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode} = 0.80 - (-0.74) = 1.54 \, V $.

NEET Chemistry: Electrochemistry — Practice Set 13

Q1. The molar conductivity of a 0.005 M solution is 80 S cm\(^2\) mol\(^{-1}\). What is the conductivity of the solution?

Q2. What is the emf of the cell \( Mn(s) | Mn^{2+}(0.005 \, M) || Hg^{2+}(0.02 \, M) | Hg(l) \) at 298 K? (Given: \( E^\circ_{Mn^{2+}/Mn} = -1.18 \, V \), \( E^\circ_{Hg^{2+}/Hg} = 0.85 \, V \))

Q3. What is the standard emf of a cell with the reaction \( Cr(s) + 3Ag^+(aq) \rightarrow Cr^{3+}(aq) + 3Ag(s) \)? (Given: \( E^\circ_{Cr^{3+}/Cr} = -0.74 \, V \), \( E^\circ_{Ag^+/Ag} = 0.80 \, V \))

Q4. How many coulombs are required to deposit 108 g of silver from an AgNO\(_3\) solution? (Atomic mass of Ag = 108 g/mol, F = 96500 C/mol)

Q5. A conductivity cell with cell constant 0.5 cm\(^{-1}\) shows a resistance of 200 Ω with a 0.02 M KCl solution. What is the molar conductivity of the solution?

Q6. A current of 0.5 A deposits 0.3175 g of Cu from CuSO\(_4\) in 3860 s. What mass of Mg would be deposited from MgCl\(_2\) with the same charge? (Atomic masses: Cu = 63.5 g/mol, Mg = 24 g/mol, F = 96500 C/mol)

Q7. In a fuel cell operating at 298 K, the cell potential decreases from 1.23 V to 1.17 V when the \( [H^+] \) at the cathode increases from 0.1 M to 1 M. What is the number of electrons involved in the cathode reaction?

Q8. What is the emf of a cell \( Ni(s) | Ni^{2+}(0.1 \, M) || Cu^{2+}(0.001 \, M) | Cu(s) \) at 298 K? (Given: \( E^\circ_{Ni^{2+}/Ni} = -0.25 \, V \), \( E^\circ_{Cu^{2+}/Cu} = 0.34 \, V \))

Q9. What is the standard emf of a cell with the reaction \( 2Al(s) + 3Cd^{2+}(aq) \rightarrow 2Al^{3+}(aq) + 3Cd(s) \)? (Given: \( E^\circ_{Al^{3+}/Al} = -1.66 \, V \), \( E^\circ_{Cd^{2+}/Cd} = -0.40 \, V \))

Q10. The limiting molar conductivity of CsCl is 153.3 S cm\(^2\) mol\(^{-1}\). If \( \lambda^\circ_{Cs^+} = 77.0 \, S \, cm^2 \, mol^{-1} \), what is \( \lambda^\circ_{Cl^-} \)?