35 Year JEE Previous Year Questions: Electrochemistry

Which of the following reaction is possible at anode?

When the sample of copper with zinc impurity is to be purified by electrolysis, the appropriate electrodes are

[2002]

Which of the following is a redox reaction? [2002]

For a cell reaction involving a two-electron change, thestandard e.m.f. of the cell is found to be 0.295 V at 25ºC. The equilibrium constant of the reaction at 25ºC will be               [2003

Standard reduction electrode potentials of three metals A, B& C are respectively + 0.5 V, – 3.0 V & –1.2 V. The reducingpowers of these metals are [2003]

When during electrolysis of a solution of AgNO₃ 9650coulombs of charge pass through the electroplating bath,the mass of silver deposited on the cathode will be

For the redox reaction :                      
Zn(s) +Cu²⁺ (0.1M)→ Zn²⁺ (1M) + Cu(s) taking place in a cell,  is 1.10 volt. E_cell for the cell will  be                                [2003]

Several blocks of magnesium are fixed to the bottom of a ship to                   [2003]

In a hydrogen-oxygen fuel cell, combustion of hydrogenoccurs to               [2004]

Consider the following Eº values

Under standard conditions the potential for the reaction

                               [2004]

The standard e.m.f. of a cell involving one electron changeis found to be 0.591 V at 25ºC. The equilibrium constant ofthe reaction is (F = 96,500 C mol^–1; R = 8.314 JK^–1 mol^–1)                             [2004]

The limiting molar conductivities Lº for NaCl, KBr and KClare 126, 152 and 150 S cm² mol^–1 respectively. The Lº forNaBr is [2004]

In a cell that utilises the reaction  Zn_(s) + 2H⁺ (aq) → Zn²⁺+ H_2(g) addition of H₂SO₄ to cathode compartment, will          [2004]

The  values for Cr, Mn, Fe and Co are – 0.41, + 1.57, + 0.77 and + 1.97V respectively. For which one of these
metals the change in oxidation state from +2 to +3 is easiest?               [2004]

For a spontaneous reaction the DG, equilibrium constant (K) and will be respectively [2005]

The highest electrical conductivity of the following aqueoussolutions is of                     [2005]

Aluminium oxide may be electrolysed at 1000°C to furnishaluminium metal (At. Mass = 27 amu; 1 Faraday = 96,500Coulombs). The cathode reaction is– Al³⁺ + 3e^- → Al° To prepare 5.12 kg of aluminium metal by this method werequire

Calculate  using appropriate molar conductances of the electrolytes listed above at infinite dilution in H₂O
at 25°C

Which of the following chemical reactions depict the oxidizing beahviour of H₂SO₄?

The molar conductivities and at infinite dilution in water at 25ºC are 91.0 and 426.2 S cm2/mol
respectively. To calculate  , the additional value required is

Resistance of a conductivity cell filled with a solution of an electrolyte of concentration 0.1 M is 100 W. The conductivity of this solution is 1.29 S m^–1. Resistance of the same cell when filled with 0.2 M of the same solution is 520 W. The molar conductivity of 0.2 M solution of electrolyte will be                            [2006]

The equivalent conductances of two strong electrolytes at infinite dilution in H₂O (where ions move freely through a
solution) at 25°C are given below :                              [2007]

What additional information/ quantity one needs to calculate   of an aqueous solution of acetic acid?

The cell, Zn | Zn²⁺ (1 M) || Cu²⁺ (1 M) | Cu   was allowed to be completely discharged at 298 K. The relative
concentration of  is         [2007]   

Given  The potential for the cell Cr|Cr³⁺ (0.1M)|| Fe²⁺ (0.01 M)| Fe is         [2008]

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is

At 298 K standard Gibb’s energies of formation for CH₃OH(l), H₂O(l) and and CO₂ (g) are –166.2,  –237.2 and –394.4 kJ
mol^–1 respectively. If standard enthalpy of combustion of methonal is – 726 kJ mol^–1, efficiency of the fuel cell will be:                   

[2009]

Given: 

The value of standard electrode potential for the change, Fe³⁺ (aq) + e^– →Fe²⁺ (aq) will be:               

[2009]

The Gibbs energy for the decomposition of Al₂O₃ at 500°C is as follows :

The potential difference needed for electrolytic reductionof Al₂O₃ at 500°C is at least                      [2010]

The correct order of  values with negative sign for the four successive elements Cr, Mn, Fe and Co is [2010]

The reduction potential of hydrogen half-cell will be negative if :

[2011]

The standard reduction potentials for Zn²⁺/Zn, Ni²⁺/Ni and Fe²⁺/Fe are –0.76,–0.23 and –0.44 V respectively.
The reaction X+Y²⁺ →X²⁺+Y will be spontaneous when :

Given :

Based on the data given above, strongest oxidising agentwill be : [JEE M 2013]

Resistance of 0.2 M solution of an electrolyte is 50 Ω.The specific conductance of the solution is 1.4 S m^–1.The resistance of 0.5 M solution of the same electrolyte is 280 Ω. The molar conductivity of 0.5 M solution of the electrolyte in S m² mol^–1 is:

[JEE M 2014]