Electrochemistry Questions and Answers

28 At 25 C the standard reduction potential for the half cell reaction Zn s 2H aq Zn aq H g is 0 28 V What is the reduction potential of the half cell reaction in 10M H concentration assuming all other species to be at unit concentration Universal gas constant R 8 314 J K mol Faraday constant F 96500 C mol 0 339 V 0 870 V 0 398 V 0 290 V

61 The molar conductivity of a 0 5 mol dm solution of AgNO with electrolytic conductivity of 5 76 x 10 Scm at 298 K is 1 0 086 S cm mol 44 11 52 S cm mol 2 28 8 S cm mol 3 2 88 S cm mol

Which of the following is incorrect regarding batteries Primary batteries cannot be recharged and reused again Lead storage battery is an example of secondary battery In a H O fuel cell water is electrolysed to give H and 0 In a Ni Cd battery the specific gravity of the alkaline electrolyte remains same

A chemical reaction proceeds into the following steps Step 1 2A X fast Step II X B Y slow Step III Y B Product fast The rate law for the overall reaction is 1 Rate K A 3 Rate K A B 2 Rate K B 4 Rate K A B

Ans is c option 7 How long approximate should water be electrolysed by passing through 100 amperes current so that the oxygen released can completely burn 27 66 g of diborane Atomic weight of B 10 8 a 6 4 hours b 0 8 hours c 3 2 hours 2018 Main d 1 6 hours

if the Ecell for a given reaction has a negative value then which of the following gives the correct relationship for the values of AG and Keq 1 AG 0 K 1 3 AG 0 Keq 1 44 AG 0 Ke 1 2 AG 0 Keq 1

Equal volumes of 0 015 M CH3COOH 0 015 M NaOH are mixed together What would be the molar conductivity of mixture if conductivity of CH3COONa is 6 3 10 4Scm 1 Question Type Single Correct Type 1 2 3 8 4 S cm mol 1 84 S cm2 mol 1 4 2 S cm mol 1

63 54 The pressure of H required to make the potential of H electrode zero in pure water at 298 K is 1 10 4 atm 2 10 12 atm 3 10 10 atm 4 104 atm The number of electrono d la bu umont of 1 more in 60 seco

59 At 298 K the standard reduction potentials are 1 51 V for MnO4 Mn 1 36 V for Cl Cl 1 07 V for Br Brand 0 54 V for I I At pH 3 permanganate is expected to oxidize 1 Cl and Br 2 Cl Br and I RT F 0 059V 3 Br and I 4 I only

Plz Tell me this Question is Correct or Not Sir Mam plz explain answer in very easy approach I Think that instead of Ca3 PO4 2 It Should be Ca3 S 04 2 Equivalent conductivity of Ca3 PO4 2 is related to its molar conductivity by the expression 1 eq 2m 2 eq 32m 3 eq 2 m 4 Zeq 2m 6

8 Four successive members of the first series of the transition metals are listed below For which one of them the standard potential EM M value has a positive sign 1 Cu Z 29 2 Fe Z 26 3 Co Z 27 4 Ni Z 28

This section contains 35 SINGLE CORRECT PE questions Each question has 4 choices 1 2 Read More Vapour phase refining is used for which of the following elements Ozr Ge O cu

14 The reduction potential of hydrogen half cell will be negative if 1 p H 2 atm H 1 0 M 3 p H 1 atm and H 2 0 M 2 p H 2 atm and H 2 0 M 4 p H 1 atm and H 1 0 M

Q 47 The Gibb s energy change in J for the given reaction at Cu Sn 1 M and 298 K 2 2 is 2 2 Cu s Sn aq Cu aq Sn g 2 2 E Sn Sn 0 16V E Cut Cu 0 34V Take F 96500 C mol 1

2 In a cell that utilises the reaction Zn s 2H aq Zn aq H g addition of H SO4 to cathode compartment will 1 increase the Ecell and shift equilibrium to the right 3 lower the E and shift equilibrium to the left cell 2 lower the Ece and shift equilibrium to the right 4 increase the Ecell and shift equilibrium to the left cell

1 Read the passage given below and answer the following questions 1 4 4 A galvanic cell consists of a metallic zinc plate immersed in 0 1 M Zn NO3 2 solution and metallic plate of lead in 0 02 M Pb NO3 2 solution The following questions are multiple choice questions Choose the most appropriate answer i How will the cell be represented a Zn s Zn aq Pb aq Pb s b Zn s Zn aq Pb aq Pb s c Pb aq Pb s Zn s Zn aq d Pb s Pb aq Zn s Zn aq ii Calculate the emf of the cell a 6 01 V c 0 609 V iii What product is obtained at cathode a Zn 0 412 V b d 4 12 V b Pb d Pb c Zn iv Which of the following statement is not correct about an inert electrode in a cell a It does not participate in the cell reaction b It provides surface either for oxidation or for reduction reaction c It provides surface for conduction of electrons d It provides surface for redox reaction

Zn Zn Ag Ag 0 01 M 1L 0 1 M 1 EAg Ag 0 8 V E2 2n 0 77 V If x L of H O is added in anodic chamber and y L of H O is added in cathodic chamber such that emf of ce more than Ecell The possible value of x and y are X A 90 B 25 C 31 D 13 y 10 4 5 3

4 Given the following concentrations note the abnormal values for Nat in the ICF and K in the ECF K 150 mM ICF ECF 1 5 mM b In the case above if the membrane is permeable only to K what would be the predicted membrane potential Na 50 mM 160 mM a Calculate the equilibrium potentials of K Na CI using the Nernst equation Logarithm table Ex log 0 01 2 log 0 1 1 log 1 0 log 3 2 0 5 ENa log 10 1 Ec log 100 2 c If the membrane is equally permeable to K and Cr and impermeable to all other ions what would be the predicted membrane potential CI 15 mM 150 mM

34 90 Consider the process E x Volt BrO3 Value of Mark for Review E Bro3 2Br x1 x Volt Bro is O 2 x x 3 Volt 4 x x Volt 4x x Volt 5 E x Volt TIN 01 hr Br

Which of the following is incorrect regarding batteries 1 Primary batteries cannot be recharged and reused again 2 Lead storage battery is an example of secondary battery 3 In a H O2 fuel cell water is electrolysed to give H and O 4 In a Ni Cd battery the specific gravity of the alkaline electrolyte remains same

The Ksp of Ag CrO AgCl AgBr and Agi are respectively 1 1 x 10 12 1 8 x 10 10 5 0 10 13 8 3 x 10 17 Which one of the following salts will precipitate last if AgNO solution is added to the solution containing equal moles of NaCl NaBr Nal and Na CrO AIPMT 2015 1 Ag CrO4 2 Agl 3 AgCl 4 AqBr

9 The specific conductivity of a saturated solution of silver chloride is 2 x 10 Scm at 25 C What will the solubility of silver chloride at 25 C if molar conductivities at infinite dilution of Ag and CT ions are and 80 Scm mol respectively A 1 428 x 10 M B 2 382 x 10 M D 4 2 x 10 M Ans A C 2 33 x 10 M

Consider an electrochemical cell A s A aq 2M B2 aq 1 M B s The value of AH for the cell reaction is twice that of AG at 300K If the emf of the cell is zero the AS in JK mol of the cell reaction per mole of B formed at 300 K is Given In 2 0 7 R universal gas constant 8 3 JK mol H S and G are enthalpy entropy and Gibbs energy respectively 41 6

Standard potentials E for some half reactions are given below 1997 2 1 Sn 2e Sn E 0 15 V 2 2 Hg 2e Hg 2 E 0 92 V 3 PbO 4H 2e Pb 2H O E 1 45 V Based on the above which one of the following statements is correct a Sn4 is a stronger oxidising agent than Pb4 b Sn is a stronger reducing agent than Hg 2 c Hg2 is a stronger oxidising agent than Pb4 d Pb2 is a stronger reducing agent than Sn

2 1 The moles of electrons required to deposit 1 gm equivalent aluminium at wt 27 from a solution of aluminium chloride will be Anonymous Quiz 51 3

Given that E 2 F6 0 44VE 2 Fe3 0 77V if Fe Fe3 and Fe solid are kept together then Fest increases Fest decreases Fe Fest remain unchanged Fert decreases 2 3 4 brrect Answer 2 atus

The conductivities at infinite dilution of NH CI NaOH and NaCl are 130 218 120 ohm 1cm eq 1 If N solution of NH OH equivalent conductance of 100 is 10 then degree of dissociation of NH OH at this dilution is 1 0 005 3 0 01 2 0 043 4 0 02

An aqueous solution of sodium acetate is subjected to Kolbe s electrolysis to prepare ethane If a current of 5 A is passed for 1930 sec then total volume of all gases collected STP is 2 24 L 4 48 L 5 6 L 11 2 L

4 5 g of aluminium at mass 27 amu is deposited at cathode from Al 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 a 44 8 L 2005 6 11 2L b 22 4L d 5 6L

9 For the cell Pt H HC Cu Cu Ecell can be decreased by 1 4 1 increasing pressure of H gas 2 increasing Cu2 in cathodic compartme F 3 Increasing the pH in anodic half cell 4 Addition of H SO in anodic half cell

7 The standard e m f of a galvanic cell involving cell reaction with n 2 is found to be 0 295 V at 25 C The equilibrium constant of the reaction would be Given F 96500 C mol 1 R 8 314 J K mol 1 2 0 x 1011 ne 2 4 0 x 1012 3 1 0 10 4 1 0 1010

In order to calculate the ionic product of water accurately the following galvanic cell is used Pt s H g 0 01 atm KOH KCl aq AgCl s Ag s 0 1M 0 01M By measuring cell potential at appropriate concentration the value of ionic product can be calculated Assuming KOH and KCl to be completely dissociated and EC aq AgCl s Ag 0 3 V If E at 320 K is 1 02 V Determine the value of Kw x 10 4 at 320 K cell Give 2 303xRx320 F 0 06

63 Electrode potential data are given below E 0 77 V 57 3 Fe aq e Al 3e Br2 aq 2 aq Fe Al s Al s E 1 66 V MO 2e 2Br aq E 1 66 V Based on the above data which statement s is incorrect 1 Fe2 is stronger reducing agent than Br 2 Fe is stronger oxidising agent than Al 3 Al is stronger reducing agent than Fe2 4 Br is stronger reducing agent than Al 2

Q 35 Consider the following cell 1M ZnSO4 I KNO3 1 M 1 CuSO4 1M II Porous Bone Given volume of solution in each compartment 1 L III Cu 0 76 V Ecu Cr 0 34 Assuming that the current with in cell is carried equally by the positive and nega ions When 0 1 F charge passed What is the concentration of NO in compartment II

8 The equivalent conductance of solution of a 32 weak monobasic acid is 8 0 mhos cm and at infinite dilution is 400 mhos cm The dissociation constant of this acid is AIPMT Prelims 2009 1 1 25 x 10 6 3 1 25 10 4 2 6 25 10 4 4 1 25 10 5

Zn s Passage 1 Porous barrier Zn2 NINO Cu2 1M 1M IM Cu t A Galvanic cell consist of three compartment as shown in figure The first compartmer contain ZnSO4 1M and III compartment contain CuSO4 1M The mid compartmen contain NaNO3 1M Each compartment contain 1 L solution 0 76 E Zn2 Cu2 Cu 0 34 concentration of Zn in first compartment after passage of 0 1 F charge will be

The electrical energy n FE produced in a Galvanic cell is a measure of decrease in free energy AG of a cell reaction i e AG nFE For all spontaneous process AG is ve The e m f of the cell reaction 2CeCl aq Zn s 2CeCl3 aq ZnCl aq Varies as E V 0 4108 0 003 T K The AS for the reaction is 1 F 96500 C 579 JK 289 5 JK 1 1158 JK1 868 5JK

hich of the following is correct 1 For H and He z 1 and molar volume at STP is less than 22 4 L 2 For H and He z 1 and molar volume at STP is greater than 22 4 L 3 For H and He z 1 and molar volume at STP is less than 22 4 L 4 For H and He z 1 and molar volume at STP is greater than 41

What is the product formed at cathode for the given setup A AIR INERT ELECTRODES KBr aq K

48 For the disproportionation of copper 2Cut Cu Cu E is Given E for Cu Cu is 0 34 V and E for Cu Cut is 0 15 V 1 0 49 V 3 0 38 V 2 0 19 V 4 0 38 V

increase with dilution 58 For a dilute solution of a strong electrolyte the variation of molar conductivity with concentration is given by 2 A A m Ac 1 Am Am Ac A 3 A A A C m 4 A A m A C

6 The values of Aeq for NH4C1 NaOH and NaCl are respectively 149 74 248 1 and 126 4 ohm cm eq The value of ANH OH is eq 1 371 44 2 271 44 V 3 71 44 4 It cannot be calculated from the data given

52 Chromium plating is applied by electrolysis to objects suspended in a dichromate solution according to the following unbalanced half reaction Cr 0 2 aq e H aq Cr s H O 1 How many hours would it take to apply a chromium plating of thickness 2 0 x 10 2 mm to a car bumper of surface area 0 25 m in an electrolysis cell carrying a current of 75 0A Density of chromium is 7 19 g cm 2 1 5 h 3 3 0 h 4 0 25 h 1 2 2 h

4 Standard electrode potentials of Fe 2e Fe and Fe 3e Fe are 0 440 V and 0 036 V respectively The sta dard electrode potential E for Fe e Fe 1 0 476 V 2 0 404 V 3 0 404 V 1 0 772 V

COO 116 Given the ionic conductance of COO 74 50 and 73 cm ohm eq respectively The equivalent COONa conductance at infinite dilution of the salt COOK 1 197 cm ohm eq 2 172 cm ohm eq 3 135 5 cm ohm eq 4 160 5 cm ohm eg 9 K and Na are is

5 As the dilution of an electrolyte increases 1 Specific conductance decreases 2 Molar conductance decreases 3 Resistance increases 4 No change takes place in conductance

The conduction of electricity through the electrolyte solution is due to 1 Movement of molecules of electrolyte 2 Movement of ions of electrolyte 3 Movement of separate atoms 4 Movement of particles of the solvent

12 The conductivities at infinite dilution of NH CI NaOH and NaCl are 130 218 120 ohm 1cm eq 1 If N equivalent conductance of solution of NH OH 100 is 10 then degree of dissociation of NH OH at this dilution is 1 0 005 3 0 01 2 0 043 4 0 02 ala 1 lsd No

Illustration 7 167 For the reactions X2Y and Z P Q occurring at two different pressure P and P respectively The ratio of the two pressure is 1 3 What will be the ratio of equilibrium constant if the degree of dissociation of X and Z are equal

The Henry s law constant for CO dissolved in water is 1 67 108 Pa at 298 K Calculate the mole fraction of CO in 1 L of soda water when packed under 2 5 atm pressure at 298 K 1 atm 101325 Pa