List of top Chemistry Questions on Electrochemistry asked in UP Board XII

Explain electrode potential and standard electrode potential. The following reaction takes place in a cell: \[ \text{Zn(s)} + \text{Co}^{2+} \rightleftharpoons \text{Co(s)} + \text{Zn}^{2+} \] Calculate the standard cell potential \(E^\circ_{cell}\) of the cell. Given: \(E^\circ_{(\text{Zn} \rightarrow \text{Zn}^{2+})} = 0.76\,\text{V}\) and \(E^\circ_{(\text{Co} \rightarrow \text{Co}^{2+})} = 0.28\,\text{V}\) (oxidation potentials).

Is the following reaction possible or not? Explain with reasons. \[Zn(NO_3)_2 + 2Ag \rightarrow 2AgNO_3 + Zn\]

In which cell does the following reaction take place? \[2H_2(g) + O_2(g) \rightarrow 2H_2O(l)\]

The most active metal among the following is:

Write the Nernst equation of the following cell at 298 K and calculate its electromotive force.
\( \text{Mg(s)} \mid \text{Mg}^{2+}\,(0.001\,M) \parallel \text{Cu}^{2+}\,(0.0001\,M) \mid \text{Cu(s)} \)
Given: \( E^\circ_{Mg^{2+}/Mg} = -2.37\,V \) and \( E^\circ_{Cu^{2+}/Cu} = 0.34\,V \). (4)

Define molar conductivity of a solution of an electrolyte and explain Kohlrausch law.

(i) Define molar conductance of the solution of an electrolyte and discuss its change with the concentration.
(ii) Calculate the electromotive force (EMF) of the following cell:
\( \text{Ni(s)} \mid \text{Ni}^{2+}(0.16\,M) \parallel \text{Ag}^{+}(0.002\,M) \mid \text{Ag(s)} \)
(Given: \( E^{\circ}_{cell} = 1.05\,V \), \( \log_{10}2 = 0.3010 \))

Describe the charging and discharging mechanism of lead storage battery with the help of chemical reactions. (1½+1½=3)

Define conductivity and molar conductivity of an electrolyte solution. Discuss the change in their value with the change in concentration of electrolyte.

Write the Nernst equation and also explain the relation between electrode potential \( (E_{cell}) \) and the equilibrium constant \( (K_c) \).

i) Define standard electrode potential. (1)
ii) Define bidentate ligand. (1)
iii) Complete the following reactions (1+1+1):
a) RX + NaOR' → ?
b) C₆H₅COCH₃ (acetophenone) + H₂/Pd-BaSO₄ → ?
c) C₆H₆ (benzene) + CO + HCl → (AlCl₃/Cu₂Cl₂) ?
OR
i) Explain standard hydrogen electrode potential with diagram. (1)
ii) Give an example of optical isomerism. (1)
iii) Complete the following reactions (1+1+1):
a) CH₃CH₂OH → (H₂SO₄, 413 K) ?
b) RCN + SnCl₂ + HCl → ?
c) C₆H₅CH₃ (toluene) + CrO₂Cl₂ + CS₂ → ?

What is Kohlrausch's law? If \( \lambda^{\circ}_m \) for NaCl, HCl and NaAc are 126.4, 425.9 and 91.0 S cm² mol^-1 respectively, find the value of \( \lambda^{\circ}_m \) for HAc. (2+2)

The resistance of a conductivity cell filled with 0.1 mol L\(^{-1}\) KCl solution is 100 \( \Omega \). If the resistance of the same cell when filled with 0.02 mol L\(^{-1}\) KCl solution is 520 \( \Omega \), find the conductivity and molar conductivity of the 0.02 mol L\(^{-1}\) KCl solution. The conductivity of a 0.1 mol L\(^{-1}\) KCl solution is 1.29 S/m.

What are fuel cells? Draw a labelled diagram of the hydrogen–oxygen fuel cell and give the reactions that occur in the cell.

Define electrode potential and emf of a cell.

What will be the Nernst equation of the cell for the following reaction?
\( 2Cr(s) + 3Cd^{2+}(aq) \rightarrow 2Cr^{3+}(aq) + 3Cd(s) \)

Explain Kohlrausch's law. If \(\Lambda^\circ_m\) for NaCl, HCl and NaAc are 126.4, 425.9 and 91.0 S cm² mol^−1, calculate \(\Lambda^\circ\) for HAc. (4)

For the following cell reaction, write the half reactions occurring at the anode and cathode and determine the electromotive force (EMF) of the cell:
\( 2Ag^+ + Cd \rightarrow 2Ag + Cd^{2+} \)
(Given, \( E^{\circ}_{Ag^+/Ag} = +0.80\ V \) and \( E^{\circ}_{Cd^{2+}/Cd} = -0.40\ V \))

Write the definition of electrode potential and cell electromotive force (emf).