List of top Chemistry Questions on Electrochemistry asked in CBSE CLASS XII

Calculate emf of the following cell at 25°C:
\(\text{Zn (s)} | \text{Zn}^{2+} (0.001M) || \text{Cd}^{2+} (0.1M) | \text{Cd (s)}\) Given: \( E^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \, \text{V}, E^\circ_{\text{Cd}^{2+}/\text{Cd}} = -0.40 \, \text{V} \)
\([ \log 10 = 1 ]\)
Arrange the following in decreasing order of their acidic strength:
\( \text{CH}_3\text{COOH}, \, \text{O}_2\text{N}-\text{CH}_2\text{COOH}, \, \text{HCOOH} \)
Complete and balance the following chemical equations: \( 3 \text{MnO}_4^- + 4 \text{H}^+ \longrightarrow ? \)
\( \text{Cr}_2 \text{O}_7^{2-} + 14 \text{H}^+ + 6 \text{Fe}^{2+} \longrightarrow ? \)
A galvanic cell can behave as an electrolytic cell when:
Calculate emf of the given cell: Mg(s) $\mid$ Mg$^{2+}$(0.1 M) $\parallel$ Cu$^{2+}$(1.0 × 10$^{-3}$ M) $\mid$ Cu(s)
Given:
$E^\circ_{\text{Cu}^{2+}/\text{Cu}} = +0.34$ V, \quad $E^\circ_{\text{Mg}^{2+}/\text{Mg}} = -2.37$ V
(log 100 = 2)
State Kohlrausch’s law of independent migration of ions.
How much electricity in terms of Faraday is required to produce 40 g of Al from molten Al$_2$O$_3$? (Given: Atomic mass of Al = 27 u)
Calculate log \(K_c\) for the following reaction at 298 K: Zn(s) + Cu$^{2+}$(aq) $\rightleftharpoons$ Zn$^{2+}$(aq) + Cu(s)
Given:
$E^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \, \text{V}$, \quad $E^\circ_{\text{Cu}^{2+}/\text{Cu}} = +0.34 \, \text{V}$
A cell and its emf is given below:
Pt (s) $\mid$ H$_2$(g, 1 bar) $\mid$ H$^+$(aq, 1 M) $\parallel$ Cu$^{2+}$(aq, 1 M) $\mid$ Cu (s)
emf of the cell = +0.34 V
Write the reduction half-reaction at cathode.
How is standard Gibbs energy for a reaction related to equilibrium constant?
Why are iron pipes usually coated with zinc?
Why does mercury cell give a constant voltage throughout its life?
Solutions of two electrolytes X and Y are diluted. Molar conductivity of X increases 25 times whereas that of Y increases 1.5 times. Which one is a stronger electrolyte?
The charge required for the reduction of 1 mol of \( MnO_4^- \) to \( MnO_2 \) is
The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 Scm-1 . Calculate its molar conductivity.
A solution of Ni(NO3)2 is electrolysed between platinum electrodes using a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode?
Write the Nernst equation and emf of the following cells at 298 K : 
(i) Mg(s) | Mg2+ (0.001M) || Cu2+(0.0001 M) | Cu(s) 
(ii) Fe(s) | Fe2+ (0.001M) || H+ (1M)|H2(g)(1bar) | Pt(s) 
(iii) Sn(s) | Sn2+(0.050 M) || H+ (0.020 M) | H2(g) (1 bar) | Pt(s) 
(iv) Pt(s) | Br2(l) | Br-  (0.010 M) || H+ (0.030 M) | H2(g) (1 bar) | Pt(s).
How much charge is required for the following reductions: 
  (i) 1 mol of Al3+  to Al. 
  (ii) 1 mol of Cu2+ to Cu. 
  (iii) 1 mol of MnO-4 to Mn2+ .
Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible: 
(i) Fe3+ (aq) and I- (aq) 
(ii) Ag+ (aq) and Cu(s) 
(iii) Fe3+(aq) and Br-(aq) 
(iv) Ag(s) and Fe3+(aq) 
(v) Br2 (aq) and Fe2+(aq).
The conductivity of sodium chloride at 298 K has been determined at different concentrations and the results are given below: 
Concentration/M 0.001 0.010 0.020 0.050 0.100 
102  × κ/S m-1  1.237 11.85 23.15 55.53 106.74 
Calculate \(\land_m\) for all concentrations and draw a plot between \(\land_m\) and c ½. Find the value of  \(\land^0_m\).
Depict the galvanic cell in which the reaction Zn(s) + 2Ag+(aq) → Zn2+(aq) + 2Ag(s) takes place. Further show: 
 (i) Which of the electrode is negatively charged? 
 (ii) The carriers of the current in the cell. 
 (iii) Individual reaction at each electrode.
In the button cells widely used in watches and other devices the following reaction takes place:
Zn(s) + Ag2O(s) + H2O(l) \(\rightarrow\) Zn2+(aq) + 2Ag(s) + 2OH-  (aq) 
Determine \(\triangle _rG^\ominus\) and \(E^\ominus\) for the reaction.
Predict the products of electrolysis in each of the following: 
 (i) An aqueous solution of AgNO3 with silver electrodes. 
 (ii) An aqueous solution of AgNO3 with platinum electrodes. 
 (iii) A dilute solution of H2SO4 with platinum electrodes. 
 (iv) An aqueous solution of CuCl2 with platinum electrodes.

Three electrolytic cells A,B,C containing solutions of ZnSO4, AgNO3 and CuSO4, respectively are connected in series. A steady current of 1.5 amperes was passed through them until 1.45 g of silver deposited at the cathode of cell B. How long did the current flow? What mass of copper and zinc were deposited?

How much electricity is required in coulomb for the oxidation of 
(i) 1 mol of H2O to O2. 
(ii) 1 mol of FeO to Fe2O3.