Electrochemistry Questions and Answers

For a electrolyte A By which of the following is correct for kohlroush law Aq x Aa Av Y A Br X B Am X Am AY y Am gr B Aeq xea Ay Bx X y Aq X Am Ax y Am By

2 For given half cell Al 3e Al on increasing Al the electrode potential 1 Increases 2 Decreases 3 No change he Istem n2 aid of 4 First increases then decreases

Consider the following electrochemical cell a Write a balanced net ionic equation for the spontaneous reaction that take place in the cell b Calculte the standard cell potential E for the cell reaction c If the cell emf is 1 6 V what is the concentration of Zn d How will the cell potential be affected if KI is added to Ag half cell Zn E AD Ag 0 8 V E12 0 76 V Zn NO3 2 Salt Bridge Ag 0 1 M AgNO

Given Sn Sn 2e E 0 66 V Fe Fe 2e E 0 33 V Most strong oxidising agent will be 2 Sn 4 Fe 1 Sn 2 3 Fe ALLEN 64 framan Sn Sn 2c E 0 66 V Fe Fe 2e E 0 33 STTUR Ses van fasech Brit 1 Sn 3 Fe 2 Sn 4 Fe

73 Given that Ni Ni 0 25 V Cu Cu 0 34 V Ag Ag 0 80 V Zn Zn 0 76 V Which of the following reactions under standard condition will not take place in the specified direction 1 Ni Cu Nis Cu aq 2 2Ag Cu s 2Ag s Cu2 2 3 Zn Cu ALLEN 73 Cu s fe Ni Ni 0 25 V Cu Cu 0 34 V Ag Ag 0 80 V Zn Zn 0 76V f fuff sta 1 N4 Cu s 2 2Ag Cu aq 3 Zn Cu aq Nis Cu 2Ag Cut Cu s 11 aq Zn

28 If the density of copper is 8 94 g cm the number of Faradays required to plate an area 10cm x 10cm of thickness of 10 2 cm using CuSO solution as electrolyte is 2 0 28 F 4 0 5 F 1 0 1 F 3 0 4 F

3 3 Zn Cu 4 2H aq Zn s H2 g If the specific conductance and conductance of a 74 solution are same then its cell constant is equal to 2 0 3 10 4 100 Zn Cu s aq 2 3 Zn Cu Zn Cu s aq H2 g 2 aq 4 2H Zn s aq fastfera un fafing art fra andre fontes 1 1 2 0 Zn aq 3 10 4 100

In the cell reaction H 2 atm H H IH p atm for spontaneous cell reaction the value of p should 1 Less than 2 atm 2 Greater than 2 atm 3 Equal to 2 atm AY Any value of pressure

2 A current of 0 965 ampere is passed through 500 ml of 0 2 M solution of ZnSO4 for 10 minutes The molarity of Zn after deposition of zinc is 1 0 1 M 2 0 5 M 3 0 8 M 18 4 0 194 M

63 Electrode potential data are given below S A 3 2 Fe aq eFe aq Fe E 0 77 V Alaq 3e Al s E 1 66 V Br2 aq 2e 2Br aq E 1 66 V Based on the above data which statement s incorrect 8 1 Fe2 is stronger reducing agent than Br 2 Fe2 is stronger oxidising agent than Al 3 Al is stronger reducing agent than Fe2 2 4 Bris stronger reducing agent than Al 2

Consider two strong electrolytes NaCl and KCI The molar conductance Am and concentration C for strong electrolytes can be related as A A B C What can be said about the values of A and B for KCI and NaCl Both have same value of A as well as B Both have same value of A but different value of B Both have different value of A but same value of B Both have different value of A as well as different value of B

An acid base indicator has K 3 0x10 The acid form of the indicator is red and the basic form is blue Then which of the following statement s is are correct Take log3 0 48 pH is 4 04 when indicator is 75 red pH is 5 00 when indicator is 75 blue pH is 5 00 when indicator is 75 red pH is 4 05 when indicator is 75 blue

9 An electrolytic cell is composed of Cu and Zn current of 9 65 A is drawn from a cell for 1 hou Then the loss in mass at anode and gain in mas at cathode respectively could be 1 11 77 g 11 43 g 3 22 86 g 23 54 g 2 11 77 g 10 g 4 23 54 a 2386

How long must a 50 0 A current be passed through an electrolytic cell fo refining copper to produce 3 00 mole of copper Options 1 O 1 50 hrs 2 O 1 61 hrs 3 O 2 50 hrs 4 O3 21 hrs

5 Which of the following is not correct 1 Molar conductance of a solution increases with dilution 2 Equivalent conductance increases with dilution 3 Specific dilution conductance increases with 4 At infinite dilution each ion cation or anion plays a definite role towards electrical conductance

Hydrazine can be used in fuel cell N H4 aq O2 g N2 g 2H O 0 If AG for this reaction is 600 kJ what will be the E for the cell 1 1 25 V 3 1 57 V 2 1 50 V 4 1 75 V

Equivalent conductivity of BaCl2 H SO4 and HCl are x x2 and x cm eq at infinite dilution If conductivity of saturated BaSO solution x 5 cm then Ksp of BaSO4 is A B D 500x X X2 2X3 105x2 X X 2X3 2 5 x 105x X X2 X3 0 25x X X2 X3

action If the standard electrode potential of Cu Cu electrode is 0 34 V what is the electrode potential of 0 1 M 2 Equilibrium constant 4 All of these 8 concentration of Cu 1 3 99 V 2 0 3105 V 3 0 222 V If Cu Cu electrode is diluted 100 times then the change in emf is 4 0 176 V

The molar conductivities of ADAC and AC are given at 25 C To calculate ADAC molar conductivity of other electrolyte required i O ANaci O ANaOH O A 0

18 The specific conductivity of N 10 KCI solution at 20 C is 0 0212 ohm 1 cm 1 and the resistance of the cell containing this solution at 20 C is 55 ohm The cell constant is ON 2 1 166 cm 1 4 3 324 cm 10 1 4 616 cm 1 3 2 173 cm 1

When two half cell of electrode potential of Ea and Eb are combined to form a cell of electrode potential E then If na n and n are no of electron exchange in 1st 2nd and combined half cell A E Eb Ea B E a En En n En E n 12 C E n D E Ea Eb

Given that 1312 8 E 3 m Fe 8 2 m so 68 ohm 1 cm mol and 80 ohm cm mol 1 ea Fe2 SO4 3 eq What will be e 148 ohm cm eq 880 ohm cm eq 364 ohm 1 cm eq 130 ohm cm eq

45 If the colour changes in an acid base indicator pKindicator 7 2 are as given below which of the following is correct HIn aq A B C D Yellow H aq In aq Pink In a strong alkaline solution pink colour will be observed In a strong acidic solution pink colour is observed In a strong alkaline solution yellow colour is observed At pH 5 5 In is more than HIn

5 Saturated solution of KNO3 is used to make salt bridge because 1 Velocity of K is greater than that of NO 2 Velocity of NO is greater than that of K 3 Velocity of K and NO3 are nearly same 4 KNO3 is highly soluble in water

8 The standard reduction potential values of three metals X Y and Z are 0 52 3 303 and 1 18V respectively The order of reducing power of the corresponding metal is 1 Y Z X 2 X Y Z 3 Z Y X 4 Z X Y

26 Calculate AG for the galvanic cell 2Cr s 3Cd aq 2Cr 3 aq 3Cd s Er 3 Cr 0 74 V EC Cd 0 40 V Senco 1 196 86 kJ mol 3 65 62 kJ mol 2 98 43 kJ mol 4 164 05 kJ mol

In electrochemistry chapter under the topic electrolysis w ith same type of electrode sir said that on electrolysis of FeSO4 we will get Fe at cathode and Fe at anode But reduction potential of Fe is smaller than H then wh y this will happen at cathode

Pre Medical Chemistry Given below are the half cell reactions Mn 2e Mn E 1 18 V 2 Mn e Mn E 1 51 V The Eo for 3Mn Mn 2Mn3 will be 1 0 33 V the reaction will not occur 2 0 33 V the reaction will occur 3 2 69 V the reaction will not occur 4 2 69 V the reaction will occur ut Explain full question ow Mainly explain how we get n 2 for resultant reaction

Consider the following statements for lead storage battery a It consists of a grid of lead packed with PbO2 as anode and a lead cathode b 38 solution of H SO4 is used as an electrolyte c It is commonly used in automobiles and invertors Which of the above statements are correct O a and c Ob and c O a and b

When Eext 1 1 volt is applied in Daniel cell having electrodes of zinc and copper dipping in one molar solutions of their respective salts then O Electrons flow from Cu to Zn O Electrons flow from Zn to Cu O Zn dissolves at anode and Cu deposits at cathode O No flow of electrons or current

1 Q 53 The solubility of Co Fe CN 6 in water at 25 C from the following data Conductivity of saturated solution of Co Fe CN 6 2 06 x 106 ohm cm and that of water 4 1 x 107 ohm cm The ionic molar conductivities of Co and Fe CN are 86 and 444 ohm cm mol respectively is 2 x 10 mol

Limiting molar conductivity of CH COOH ie Am CH3COOH is equal to O Am HCB Am NaC1 Am CH COONa O Am HCB Am CH COONS Am N CI

An aquous solution containing IM NISO and IMS O is electrolysed using palladium electrode at 25 C Ni 2 Ni E 0 25V 21 2e H E 0 00V O 4H 4e 2H O E 1 23V Pd 2 Pd E 0 92V S O 2 2SO E 2V pH of solution is 7 Select the correct statement s on the basis of given information Ignore over voltage and neglect variation with cocentration A Reaction at anode is Pd Pd 2 C Reaction at cathode is Ni 2 Ni B Reaction at anode is 2H O O 4H 4e D Reaction at cathode is 2H 2 H

A For the reaction Fe 2 aq Ag aq Ag s Fe aq Predict which change will decrease the cell voltage 1 Increase the amount of Ag 3 Increase the concentration of Fe 3 2 Decrease the concentration of A 4 Both 2 3

Q 53 The e m f of cell Zn ZnSO4 CuSO4 Cu at 25 C is 0 03 V and the temperature coefficient of e m f is 1 4 x 10 V per degree The heat of reaction for the change taking place inside the cell is kJ mol

Q 59 Dipole moment of HX is 2 59 x 10 30 coulomb metre Bond length of HX is 1 39 bns The ionic character of molecule is

Purification of chromium can be achieved by electrorefining chromium from an impure chromium anode onto a pure chromium cathode in an electrolytic cell How many hours will it take to plate 13 0 kg of chromium onto the cathode if the current passed through the cell is held constant at 41 0 A Assume the chromium in the electrolytic solution is present as Cr

The reduction potential of H electrode in a solution of 0 1 M H aq is PH 1 atm 0 0591 V 0 591 V nr min 0 0591 V

Calculate the reduction potential of a half cell having reaction Ag S s 2e 2Ag S S aq in a solution buffered at p 3 and which is also saturated with 0 1M H S aq Given K Ag S 10 Kal Ka 10 E As Ag 2 303 RT F 0 06 A 0 19V B 0 19 C 1 18V D 1 18 V 0 8V

Amount of electricity required to reduce 0 5 mole of A1 ions to Al atoms is 3 F 2 F hr 0 5 F

When electrochemical cell is changed into electrolytic cell then why sign of cathode positive only Has ncert mentioned it wrobg in the diagram pls tell corre ct explanation teacher properly c Cathode ve Zn ZnSO4 Eext 1 1 W e CuSO4 Current Anode ve Cu ii No cha reacti When Eext 1 i Electrons e from Cuper and curre from Zn t ii Zinc is de at the zind electrode a copper diss copper elec

How much amount of water can be decomposed through electrolysis by passing 2 F charge 2 5 mol of water 3 mol of water 3 5 mol of water 1 mol of water

Calculate the volume of O liberated at STP by 81 passing 5A current for 193 sec through acidified water 1 56 mL 3 158 mL 2 112 mL 4 965 mL PRIR 2912 1 5e 3 15 0500

2 F electricity was passed through molten FeO Weight of iron metal Atomic wt 56 deposited at cathode in g is 112 84 56 28

Salt bridge A concentration cell similar to the one shown is composed of twa Ph electrodes and solmons of different Pb2 concentrations The left compartment contains 1 25 M Ph and t compartment contains 2 26 162 Ph Calculate the cell potential for this reaction at 298 K volly

THE CORRECT ANSWER 9 A Daniel Cell may be represented as Zn s Cu2 aq Zn2 aq Cu s If AG 293 formation 0 for Zn s and Cu s 35 14 Kcal mol for Zn aq and 15 66 Kcal mol for Cu 2 aq calculate the E for the cell and equilibrium constant of the reaction under standard condition

In a galvanic cell Cu is reacting with nitric acid to produce NO or NO At what NO3 tendency of formation of NO NO is same E Cu Cu E 0 34V NO NO H E 0 79V 0 96V NO NO H Assume pressure of all the gases are taken as unity P NO PN NO

M The equivalent conductance of 10 Given A HA 80 ohm cm eq 2 5 x 10 4 3 5 10 3 6 5 x 10 4 5 5 10 5 solution of a weak monobasic acid HA is 4 ohm cm eq The dissociation constant of the acid will be

71 Study the given figure and answer the question that follow t A OF i Give the names of the electrodes A and B a A Cathode B Anode b A Anode B Cathode c A Anode B Anode d A Cathode B Cathode ii Which electrode is the oxidising electrode a A b B c Both a and b

5 8 S cm mol During the electrolysis of molten sodium chloride the time required to produce 0 10 mol of chlorine gas us a current of 3 amperes is 1 220 minutes 44 110 minutes 2 330 minutes 3 55 minutes 900