Electrochemistry

For the reactions

MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O ; E° = 1.51 V

MnO₂ + 4H⁺ + 2e⁻ → Mn²⁺ + 2H₂O ; E° = 1.23 V

then for the reaction MnO₄⁻ + 4H⁺ + 3e⁻ → MnO₂ + 2H₂O, E° is -

A graph of molar conductivity of three electrolytes (NaCl, HCl and NH₄OH) is plotted against √C. Which option is correct?

The standard reduction potential E° for OCl⁻/Cl⁻ = 0.86 V and Cl⁻/½Cl₂ = −1.10 V

The E° value of OCl⁻/½Cl₂ will be-

The charge required to deposit 40.5 g of Al (atomic mass = 27.0 g) from the fused Al₂(SO₄)₃ is

E°Al³⁺/Al = −1.66 V and K_sp of Al(OH)₃ = 1 × 10⁻³³.

Reduction potential of the couple at pH = 14 is-

For I₂ + 2e⁻ → 2I⁻ E°red = +0.54 V

and 2Br⁻ → Br₂ + 2e⁻ E°ox = +1.09 V

For Fe → Fe²⁺ + 2e⁻ E°ox = +0.44 V

Which reaction is non-spontaneous?

The equivalent conductivities at infinite dilution of the cation and the anion of a salt A₂B are 140 and 80 ohm^–1 cm² eq^-1 respectively. The equivalent conductivity (in ohm^–1 cm² eq^–1) of the salt at infinite dilution is-

In the given arrangement, on pressing the key, the-

The single electrode potential E of 0.1 M solution of M⁺ ions [E°_R = −2.36 V] is -

A solution containing one mol per litre each of Cu(NO₃)_2, AgNO₃, Hg₂(NO₃)₂ and MgSO₄ is being electrolysed by using inert electrodes.The standard electrode potentials (reduction potentials) are: Ag⁺/Ag = +0.80 V Hg₂²⁺/Hg = +0.79 V Cu²⁺/Cu = +0.34 V Mg²⁺/Mg = −2.37 V With increasing voltage, the sequence of deposition of metals on the cathode will be-

Standard electrode potentials of

Fe²⁺ + 2e⁻ → Fe ; E° = −0.440 V

Fe³⁺ + 3e⁻ → Fe ; E° = −0.036 V

The standard electrode potential (E°) for Fe³⁺ + e⁻ → Fe²⁺ is -

The reaction ½H₂(g) + AgCl(s) → H⁺(aq) + Cl⁻(aq) + Ag(s)

can be represented in the galvanic cell as-

For the cell prepared from electrodes A and B

A : Cr₂O₇²⁻ / Cr³⁺ ; E°red = +1.33 V

B : Fe³⁺ / Fe²⁺ ; E°red = +0.77 V

Which statement(s) is/are correct-

The standard EMF of the cell reaction

$\frac{1}{2}\mathrm{Cu}(\mathrm{s})+\frac{1}{2}\mathrm{C}{\mathrm{l}}_2(\mathrm{g})\to \frac{1}{2}\mathrm{C}{\mathrm{u}}^{2+}+\mathrm{C}{\mathrm{l}}^{-}$

is 1.02 V. The value of ∆0G° will be

The e.m.f. of the cell involving the reaction

2Ag⁺ + H₂ → 2Ag + 2H⁺ is 0.80 V.

The standard oxidation potential of silver electrode is-

When copper sulphate solution is electrolysed in a copper voltameter for 30 s, m gram of copper was deposited. Time-current graph is given. The electrochemical equivalent of copper from above plot will be-

The reduction potential of the two half cell reactions are

PbSO₄ + 2e⁻ → Pb + SO₄²⁻ E° = –0.31 V

Ag⁺ + e⁻ → Ag E° = +0.80 V The feasible reaction will be-

The standard reduction potential of Pb and Zn electrodes are –0.126 V and –0.763 V respectively. The e.m.f. of the cell

Zn | Zn²⁺(0.1 M) || Pb²⁺(1 M) | Pb is-

At 298 K, the standard reduction potentials are:

Zn²⁺/Zn = −0.762 V

Cr³⁺/Cr = −0.740 V

2H⁺/H₂ = 0.00 V

Fe³⁺/Fe²⁺ = +0.770 V

The strongest reducing agent is-

At 25°C molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is 9.54 ohm^–1 cm² mol^–1 and at infinite dilution its molar conductance is 238 ohm^–1 cm² mol^–1. The degree of ionization of ammonium hydroxide at the same concentration and temperature is :

Match List-I with List-II

The correct option is

The standard oxidation potentials are:

Zn → Zn²⁺ + 2e⁻ ; E° = 0.76 V

Fe → Fe²⁺ + 2e⁻ ; E° = 0.41 V

The emf for the reaction Fe²⁺ + Zn → Zn²⁺ + Fe is-

Consider the following electrolytes:

1. AgNO₃ 2. CuSO₄ 3. AlCl₃ 4. Bi₂(SO₄)₃

The quantity of electricity needed to electrolyse separately 1 M solutions of these electrolytes will be-

4.5 g of aluminium (at. mass 27 amu) is deposited at cathode from Al³⁺ solution by a certain quantity of electric charge. The volume of hydrogen produced at STP from H⁺ ions in solution by the same quantity of electric charge will be:

The reaction for the cell,

Zn | Zn²⁺(1.0 M) || Cd²⁺(1.0 M) | Cd is-

Consider a voltaic cell based on these half-cells

Ag⁺ + e⁻ → Ag ; E° = +0.80 V

Cd²⁺ + 2e⁻ → Cd ; E° = −0.40 V

Identify the anode and give the voltage of the cell under standard conditions -

For a reaction A(s) + 2B⁺ → A²⁺ + 2B

K_C has been found to be 10¹². The E°cell is-

In the arrangement shown, the arrow represents-

Which of the following will increase the voltage of the cell

Sn(s) + 2Ag⁺(aq) → Sn²⁺(aq) + 2Ag(s)

Three faraday of electricity is passed through molten solutions of AgNO₃, NiSO₄ and CrCl₃ kept in three vessels using inert electrodes. The ratio in mol in which the metals Ag, Ni and Cr will be deposited is-

The molar conductances of NaCl, HCl and CH₃COONa at infinite dilution are 126.45 , 426.16 and 91 ohm^–1 cm² mol^–1 respectively. The molar conductance of CH₃COOH at infinite dilution in ohm^–1 cm² mol^–1 is

A fuel cell involves combustion of butane at 1 atm and 298 K,

C₄H₁₀ + 13/2 O₂ → 4CO₂ + 5H₂O ΔG° = −2746 kJ mol⁻¹

What is E°cell?

Zn + Cu²⁺ ⇌ Cu + Zn²⁺ , Q = [Zn²⁺]/[Cu²⁺]

Variation of Ecell with logQ is shown. OA = 1.10 V. Ecell will be 1.1591 V when-

Standard cell voltage for the cell Pb/Pb²⁺ ||Sn²⁺/Sn is −0.01V. If the cell is to exhibit Ecell = 0, the value of [Sn²⁺]/[Pb²⁺] should be antilogs of (approx)

The number of electrons delivered at the cathode during electrolysis by a current of 1 ampere in 60 seconds is : [Charge on electron is = 1.6 × 10^–19 C]

Which among the following transition elements has positive E°_M²⁺/M value ?

Below plot represents variation of molar conductance against √C. Select the correct option.

The following facts are available:

2A⁻ + B₂ → 2B⁻ + A₂

2C⁻ + B₂ → No reaction

2D⁻ + A₂ → 2A⁻ + D₂ Which statement is correct-

What is the % dissociation of CH₃COOH, if equivalent conductivity at this dilution and at infinite dilution are 148 and 398 S cm²/mol respectively ?

Given

Ag⁺/Ag = +0.80 V

Co²⁺/Co = –0.28 V

Cu²⁺/Cu = +0.34 V

Zn²⁺/Zn = –0.76 V

The most reactive metal which displaces other metals from their salt solution is-

Consider the following half-cell reactions:

I. A + e⁻ → A⁻ E° = +0.96 V

II. B⁻ + e⁻ → B²⁻ E° = −0.12 V

III. C⁺ + e⁻ → C E° = +0.18 V

IV. D²⁺ + 2e⁻ → D E° = −1.12 V

What combination of two half-cells would result in a cell with the largest potential?

Consider the following equations for a cell reaction

A + B ⇌ C + D ; E° = x volt, Keq = K₁

2A + 2B ⇌ 2C + 2D ; E° = y volt, Keq = K₂ then :

A student made the following observations:

(i) Clean copper metal did not react with 1 M Pb(NO₃)₂ solution

(ii) Clean lead metal dissolved in 1 M AgNO₃ solution and crystals of Ag appeared

(iii) Clean silver metal did not react with 1 M Cu(NO₃)₂ solution

The order of decreasing reducing character of the three metals is-