Electrochemistry

Given at 298 K : E Fe2+/Fe = X Volt E Fe3+/Fe = Y Volt The E Fe3+/Fe2+ in Volt at 298 K is given by :

1. 2X − 3Y
2. 3Y − 2X
3. 3Y + 2X
4. Y + X

Consider the following data. arraycc Electrolyte & m ( S cm2 mol-1) \ BaCl2 & x1 \ H2SO4 & x2 \ HCl & x3 array BaSO4 is sparingly soluble in water. If the conductivity of the saturated BaSO4 solution is x S cm-1 then the solubility product of BaSO4 can be given as (Here m = m)

1. 106x2 2(x1 + x2 - 2x3)2
2. x2(x1 + x2 - 2x3)2
3. 2(x1 + x2 - 2x3)2106x2
4. x2(x1 + x2 + 2x3)2

For a general redox reaction Anode Red1 Ox1n1+ + n1e- Cathode Ox2 + n2e- Red2n2- Which of the following statement is incorrect?

1. The overall reaction can be written as n2Red1 + n1Ox2 n2Ox1n1+ + n1Red2n2-
2. The electrons do not appear in the overall reaction because electrons produced at the anode are consumed at the cathode.
3. [figure] Here n is the number of electrons transferred in redox reaction.
4. If the reaction is carried out reversibly, the electrical work done is equal to the ratio of charge and potential difference through which charge is moved.

One half cell in a voltaic cell is constructed by dipping silver rod in AgNO3 solution of unknown concentration, other half cell is Zn rod dipped in 1 molar solution of ZnSO4. A voltage of 1.60 V is measured at 298 K for this cell. What is the concentration of Ag+ ions used in terms of log x (x = [Ag+])? E Zn2+/Zn = −0.76 V, E Ag+/Ag = +0.80 V, 2.303RTF = 0.059 V

1. 23.9
2. 45.9
3. 2.92
4. 5.94

An electrochemical cell is constructed using half cells in the direction of spontaneous change: Fe(OH)2(s) + 2e- Fe(s) + 2OH-(aq) E = -0.88 V and AgBr(s) + e- Ag(s) + Br-(aq) E = +0.07 V Which of the following options is correct?

1. Overall reaction Fe(s) + 2OH-(aq) + 2AgBr(s) Fe(OH)2(s) + 2Ag(s) + 2Br-(aq)
2. E cell = -0.95 V
3. Fe is reduced in the electrochemical cell
4. E cell is an extensive property

In the given electrochemical cell, Ag(s)|AgCl(s)|FeCl2(aq), FeCl3(aq) | Pt(s) at 298 K, the cell potential ( Ecell) will increase when : Choose the correct answer from the options given below :

1. C, D and E Only
2. A and B Only
3. B Only
4. A and E Only

[figure] Consider the above electrochemical cell where a metal electrode (M) is undergoing redox reaction by forming M+ (M M+ + e-). The cation M+ is present in two different concentrations c1 and c2 as shown above. Which of the following statement is correct for generating a positive cell potential?

1. If c1 is present at anode, then c1 > c2.
2. If c1 is present at cathode, then c1 > c2.
3. If c1 is present at cathode, then c1 < c2.
4. If c1 is present at anode, then c1 = c2.

Consider the following reduction processes : Al3+ + 3e- Al(s), E0 = -1.66 V Fe3+ + e- Fe2+, E0 = +0.77 V Co3+ + e- Co2+, E0 = +1.81 V Cr3+ + 3e- Cr(s), E0 = -0.74 V The tendency to act as reducing agent decreases in the order :

1. Al > Fe2+ > Cr > Co2+
2. Al > Cr > Co2+ > Fe2+
3. Cr > Fe2+ > Al > Co2+
4. Al > Cr > Fe2+ > Co2+

For a closed circuit Daniell cell, which of the following plots is the accurate one at a given temperature?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Given below are two statements : In the light of the given statements, choose the correct answer from the options given below :

1. Both Statement I and Statement II are true
2. Statement I is true but Statement II is false
3. Both Statement I and Statement II are false
4. Statement I is false but Statement II is true

Given below are two statements : 1 M aqueous solutions of each of Cu(NO3)2, AgNO3, Hg2(NO3)2, Mg(NO3)2 are electrolysed using inert electrodes. Given: E0Ag+/Ag = 0.80 V, E0Hg22+/Hg = 0.79 V, E0Cu2+/Cu = 0.34 V and E0Mg2+/Mg = -2.37 V. In the light of the above statements, choose the most appropriate answer from the options given below :

1. Both Statement I and Statement II are incorrect
2. Statement I is incorrect but Statement II is correct
3. Statement I is correct but Statement II is incorrect
4. Both Statement I and Statement II are correct

On charging the lead storage battery, the oxidation state of lead changes from x1 to y1 at the anode and from x2 to y2 at the cathode. The values of x1, y1, x2, y2 are respectively :

1. 0, +2, +4, +2
2. +2, 0, 0, +4
3. +4, +2, 0, +2
4. +2, 0, +2, +4

Correct order of limiting molar conductivity for cations in water at 298 K is :

1. H+ > Na+ > K+ > Ca2+ > Mg2+
2. H+ > Ca2+ > Mg2+ > K+ > Na+
3. Mg2+ > H+ > Ca2+ > K+ > Na+
4. H+ > Na+ > Ca2+ > Mg2+ > K+

The standard cell potential ( E cell ) of a fuel cell based on the oxidation of methanol in air that has been used to power television relay station is measured as 1.21 V. The standard half cell reduction potential for O2 ( E O2/H2O ) is 1.229 V. Choose the correct statement :

1. Reactants are fed at one go to each electrode.
2. Oxygen is formed at the anode.
3. The standard half cell reduction potential for the reduction of CO2 ( E CO2/CH3OH ) is 19 mV
4. Reduction of methanol takes place at the cathode.

40 mL of a mixture of CH3COOH and HCl (aqueous solution) is titrated against 0.1 M NaOH solution conductometrically. Which of the following statement is correct? [figure]

1. The concentration of CH3COOH in the original mixture is 0.005 M
2. The concentration of HCl in the original mixture is 0.005 M
3. CH3COOH is neutralised first followed by neutralisation of HCl
4. Point 'C' indicates the complete neutralisation of HCl

For a Mg | Mg2+(aq) || Ag+(aq) | Ag the correct Nernst Equation is :

1. Ecell = E cell - RT2F [Ag+]2[Mg2+]
2. Ecell = E cell - RT2F [Mg2+][Ag+]
3. Ecell = E cell - RT2F [Ag+][Mg2+]
4. Ecell = E cell + RT2F [Ag+]2[Mg2+]

The molar conductivity of a weak electrolyte when plotted against the square root of its concentration, which of the following is expected to be observed?

1. Molar conductivity increases sharply with increase in concentration.
2. Molar conductivity decreases sharply with increase in concentration.
3. A small increase in molar conductivity is observed at infinite dilution.
4. A small decrease in molar conductivity is observed at infinite dilution.

O2 gas will be evolved as a product of electrolysis of : Choose the correct answer from the options given below :

1. (B) and (C) only
2. (B) and (D) only
3. (A) and (D) only
4. (A) and (C) only

For the given cell Fe2+(aq) + Ag+(aq) Fe3+(aq) + Ag(s) The standard cell potential of the above reaction is Given: Ag+ + e- Ag E = xV Fe2+ + 2e- Fe E = yV Fe3+ + 3e- Fe E = zV

1. x + 2y - 3z
2. x + 2y
3. y - 2x
4. x + y - z

Based on the data given below : E (Cr2O72-/Cr3+)=1.33 V E (Cl2/Cl-)=1.36 V E (MnO4-/Mn2+)=1.51 V E (Cr3+/Cr)=-0.74 V the strongest reducing agent is :

1. Cl-
2. MnO4-
3. Cr
4. Mn2+

FeO42- +2.0 V Fe3+ 0.8 V Fe2+ -0.5 V Fe0 In the above diagram, the standard electrode potentials are given in volts (over the arrow). The value of E (FeO42-/Fe2+) is :

1. 1.2 V
2. 2.1 V
3. 1.4 V
4. 1.7 V

Standard electrode potentials for a few half cells are mentioned below : E Cu2+/Cu = 0.34 V, E Zn2+/Zn = -0.76 V E Ag+/Ag = 0.80 V, E Mg2+/Mg = -2.37 V Which one of the following cells gives the most negative value of G ?

1. Zn | Zn2+(1M) || Ag+(1M) | Ag
2. Ag | Ag+(1M) || Mg2+(1M) | Mg
3. Zn | Zn2+(1M) || Mg2+(1M) | Mg
4. Cu | Cu2+(1M) || Ag+(1M) | Ag

Which of the following electrolyte can be used to obtain H2S2O8 by the process of electrolysis ?

1. Concentrated solution of sulphuric acid
2. Dilute solution of sodium sulphate.
3. Acidified dilute solution of sodium sulphate.
4. Dilute solution of sulphuric acid

A solution of aluminium chloride is electrolysed for 30 minutes using a current of 2 A. The amount of the aluminium deposited at the cathode is . [Given : molar mass of aluminium and chlorine are 27 g mol-1 and 35.5 g mol-1 respectively. Faraday constant = 96500 C mol-1]

1. 1.660 g
2. 1.007 g
3. 0.336 g
4. 0.441 g

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

1. Both Statement I and Statement II are true
2. Both Statement I and Statement II are false
3. Statement I is true but Statement II is false
4. Statement I is false but Statement II is true