IISER Chemistry - Electrochemistry
Exam Duration: 45 Mins Total Questions : 30
In the above question,the ion discharged at the anode is
- (a)
hydrogen
- (b)
oxygen
- (c)
hydrogen
- (d)
sulphate
Equivalent conductance of KCl at infinite dilution is 149.86 and that NaCl is 126.45 mhos cm2.Although at infinite dilution each electrolyte is completely ionised,the equivalent conductances differ because of
- (a)
strong ionic character of KCl as compared to NaCl
- (b)
difference in \(\lambda^{\infty}\) of Na+ and K+ ions
- (c)
difference in \(\lambda^{\infty}\) of K+ and Cl- ions
- (d)
difference in \(\lambda^{\infty}\) of Na+ and \(\lambda^{\infty}\) of Cl- ions
Which of the following reaction takes place at the anode during the electrolysis of fused sodium chloride?
- (a)
oxidation of chloride ion
- (b)
oxidation of sodium ion
- (c)
reduction of chlorine atom
- (d)
reduction of sodium ion
which one of the following is redox reaction?
- (a)
Fe3+ +e\(\longrightarrow\) Fe2+
- (b)
Sn+Cl2 \(\longrightarrow\) SnCl2
- (c)
Sn4++2e \(\longrightarrow\) Sn2+
- (d)
Cl2+2e\(\longrightarrow\) 2Cl-
From the following data
2Hg \(\longrightarrow\) Hg22+ +2e; E0=-0.763 volt.....(i)
Hg\(\longrightarrow\) Hg2++2e; E0=-0.851 volt....(ii)
The E0 values for the half cell
2Hg2++2e \(\longrightarrow\) Hg22+ is
- (a)
1.614 volt
- (b)
-0.088 volt
- (c)
0.088 volt
- (d)
-1.614 volt
The following reaction describes the rusting of iron.
4Fe+3O2\(\longrightarrow\) Fe3+ +6O2-
Which one of the following statements is incorrect?
- (a)
This is an example of redox reaction
- (b)
Metalic iron is reduced to Fe3+
- (c)
Fe3+ is an oxidizing agent
- (d)
Metalic iron is a reducing agent
The half cell potential at 298k for the reaction
Cu2+ (aq) +2e\(\longrightarrow\) Cu(s) with [Cu2+]=5.0M and Eo for Cu2+/Cu=0.34 volt,is found to be
- (a)
0.32v
- (b)
0.34v
- (c)
0.36v
- (d)
-0.34v
Saturated solution of KNO3 is used to make salt bridge because
- (a)
velocity of K+ is greaterv than that of NO-3
- (b)
velocity of NO-3 is greater than that of K+
- (c)
velocities of both K+ and NO-3 are nearly the same
- (d)
KNO3 is highly soluble in water
At infinite dilution ,the molar conductivity in 5 cm2 mol-1 units for various electrolytes is given as HCl =426,NaCl=126,CH3COONa=91.From these data ,the calculated value of molar conductivity at infinite dilution for CH3COOH will be
- (a)
391
- (b)
335
- (c)
300
- (d)
217
The cell constant is product of resistance and
- (a)
molar conductance
- (b)
specific conductance
- (c)
equivalent conductance
- (d)
None
The unit of electrochemical equivalent is
- (a)
coulomb g-1
- (b)
g-ampere
- (c)
g ampere-1
- (d)
g coulomb-1
The value of K for the reaction \(CH_3COOH+C_2H_5OH\longrightarrow CH_3COOC_2H_5+H_2O\) IS 4 at 250C .The value of G for the above reaction would be approximately
- (a)
-2.5 KJ mol-1
- (b)
-3.5KJ mol-1
- (c)
-4.5KJ mol-1
- (d)
NONE OF THE ABOVE
The standard reduction potential E0 Zn2+/Zn is -0.76 v and E0 Fe2+/Fe=-0.45 v Daniel cell is
- (a)
+1.10v
- (b)
-1.10v
- (c)
-0.76
- (d)
-0.42
The standard reduction potentials of Sn2+/Sn,Zn2+/Zn,Fe2+/Fe are respectively -0.14 v,-0.76v and -0.44 v. pick out the correct statement
- (a)
Corrosion of tin can be prevented by coating with Zinc
- (b)
Corrosion of zinc can be prevented by coating with tin
- (c)
Corrosion of zinc can be prevented by coating with Fe
- (d)
Corrosion of iron can be prevented by coating with tin
In a lead storage battery the reaction that occurs at anode during discharge is
- (a)
\(Pb+SO_4^{2-}\longrightarrow PbSO_4+2e\)
- (b)
\(PbO_2+4H+SO_4^{2-}2e\longrightarrow PbSO_4+2H_2O\)
- (c)
\(PbSO_4+2e\longrightarrow Pb+SO_4^{2-}\)
- (d)
\(PbSO_4+2H_2O\longrightarrow PbO_2+SO_4^{2-}+4H^{+}+2e\)
What is the emf of the cell? Cr|Cr3+(1.0 M) || Cq2+(1.0M)||Cq2+ (0.1M)|Cq (E0 for Cr3+|Cr =-0.74 volt and E0 for Co2+/Co=-0.28 volt)
- (a)
-1.02 volt
- (b)
-0.46 volt
- (c)
+0.46 volt
- (d)
1.66 volt
The cell constant of a conductivity cell
- (a)
changes with change of electrolyte
- (b)
change with change of concentration of electrolyte
- (c)
changes with temperature of electrolyte
- (d)
remains constant for a cell
The conductivity of a 0.01 N solution is found to be 0.005 \({ \Omega }^{ -1 }{ cm }^{ 2 }\). The equivalent conductivity of the solution will be
- (a)
\(5\times { 10 }^{ -2 }{ \Omega }^{ -1 }{ cm }^{ 2 }{ equiv }^{ -1 }\)
- (b)
\(5.00\times { 10 }^{ -3 }{ \Omega }^{ -1 }{ cm }^{ 2 }\)
- (c)
\(500\quad { \Omega }^{ -1 }{ cm }^{ 2 }{ equiv }^{ -1 }\)
- (d)
\(0.5\quad { \Omega }^{ -1 }{ cm }^{ 2 }{ equiv }^{ -1 }\)
An electrochemical cell can behave like an electrolytic cell when
- (a)
Ecell = 0
- (b)
Ecell > Eext
- (c)
Eext > Ecell
- (d)
E cell = Eext
The standard electrode potentials for the reactions,
\({ Ag }^{ + }(aq)+{ e }^{ - }\longrightarrow Ag(s)\) \({ S }n^{ 2+ }(aq)\ +\ 2{ e }^{ - }\longrightarrow Sn(s)\) at \({ 25 }^{ \circ }C\) are 0.80 V and -0.14 V, respectively.
The emf of the cell, \(Sn\ |\ { S }n^{ 2+ }(1M)\ ||\ Ag^{ + }(1M)\ |Ag\ \) is
- (a)
0.48 V
- (b)
0.80 V
- (c)
1.08 V
- (d)
0.94 V
Calculate the emf of the following cell at \({ 25 }^{ \circ }C\) \(\underset { 2\ atm }{ { Pt\ H }_{ 2 } } |HCI|\underset { 10\ atm }{ { H }_{ 2 }\ Pt } \)
- (a)
-0.0206 V
- (b)
+0.0206 V
- (c)
+0.8056 V
- (d)
-0.8056 V
For the following metals A, B, C, D react with each other.
\(A+{ B }^{ - }\longrightarrow No\ reaction\)
\(B+{ C }^{ + }\longrightarrow No\ reaction\)
\(B+{ D }^{ - }\longrightarrow B^{ + }+{ D }\)
\(C+{ D }^{ + }\longrightarrow C^{ + }+{ D }\)
\(A^{ + }+{ C }\longrightarrow C^{ + }+{ A }\)
\(D+{ A }^{ + }\longrightarrow D^{ + }+{ A }\)
What is the order of the metal in the increasing reducing strength?
- (a)
B < D < A < C
- (b)
C < B < D < A
- (c)
A < D < B < C
- (d)
D < C < A < B
The cell, Zn | Zn2+(1M) || Cu2+(1M) | Cu was allowed to be completely discharged at 298 K. The relative concentration of \(\left( \frac { \left[ { Zn }^{ 2+ } \right] }{ \left[ Cu^{ 2+ } \right] } \right) \) is
- (a)
antilog (24.08)
- (b)
37.2
- (c)
1037.2
- (d)
9.65\(\times\)104
The equivalent conductance of silver nitrate solution at \({ 25 }^{ \circ }C\) for an infinite dilution was found to be 133.3 ohm-1 cm 2equiv -1. The transport number of Ag+ ions in very dilute solution of AgNO 3 is 0.464. Calculate the equivalent conductance of \({ NO }_{ 3 }^{ - }(in\quad { \Omega }^{ -1 }{ cm }^{ 2 }{ equiv }^{ -1 })\) at infinite dilution.
- (a)
61.9
- (b)
195.2
- (c)
133.3
- (d)
71.4
For the following cell with hydrogen electrodes at two different pressures p1 and p2. \(\underset { p1 }{ Pt\left( { H }_{ 2 } \right) } |\underset { 1M }{ { H }^{ + }\left( aq \right) } |\underset { p2 }{ Pt\left( { H }_{ 2 } \right) } \) emf is given by
- (a)
\(\frac { RT }{ F } { log }_{ e }\frac { { p }_{ 1 } }{ { p }_{ 2 } } \)
- (b)
\(\frac { RT }{ 2F } { log }_{ e }\frac { { p }_{ 1 } }{ { p }_{ 2 } } \)
- (c)
\(\frac { RT }{ F } { log }_{ e }\frac { { p }_{ 2 } }{ { p }_{ 1 } } \)
- (d)
\(\frac { RT }{ 2F } { log }_{ e }\frac { { p }_{ 2 } }{ { p }_{ 1 } } \)
A certain current liberates 0.500 g of H in 2.00 hr. How 2 in 2.00 hr. How many gram of oxygen can be liberated by the same current in the same time?
- (a)
0.500 g
- (b)
8.00 g
- (c)
4.00 g
- (d)
16.00 g
The standard potential of a cell using the reaction, \({ 2MnO }_{ 4 }^{ - }(aq)+3Hg(l)+{ H }_{ 2 }O\rightleftharpoons 2MnO_{ 2 }(s)+3HgO(s)+2OH(aq)\)is 0.489 V at \({ 25 }^{ \circ }C\) . What is the equilibrium constant of the reaction?
- (a)
3.631 \(\times\) 1049
- (b)
3.631 \(\times\) 10-49
- (c)
4.831 \(\times\) 1027
- (d)
4.831 \(\times\) 10-27
Calculate the potential corresponding to the following cell.
Given \(Pt|{ Co }^{ 2+ }(2.0M),{ Co }^{ 3+ }(0.01M)||{ Cr }^{ 3+ }(0.5M),\quad { Cr }_{ 2 }{ O }_{ 7 }^{ 2- }(4.0M),{ H }^{ + }(1.5M)|Pt\)\({ E }_{ { Co }^{ 2+ }/{ Co }^{ 3+ } }^{ \circ }=-1.82V,\quad { E }_{ { Cr }_{ 2 }{ O }_{ 7 }^{ 2- }/{ Cr }^{ 3+ } }^{ \circ }=+1.33V\)
- (a)
-0.32 V
- (b)
+0.32 V
- (c)
0.44 V
- (d)
+0.44 V
Given \({ E }_{ { Cr }^{ 3+ }/{ Cr } }^{ \circ }=-0.74V\) \({ E }_{ Mn{ O }_{ 4 }^{ - }/{ Mn }^{ 2+ } }^{ \circ }=1.51V\)
\({ E }_{ { Cr }_{ 2 }{ O }_{ 7 }^{ 2- }/{ Cr }^{ 3+ } }^{ \circ }=1.33V\) \({ { E }^{ \circ } }_{ CI/{ CI }^{ - } }=1.36V\)
Based on the data given above strongest oxidising agent will be
- (a)
CI
- (b)
Cr3+
- (c)
Mn2+
- (d)
\({ MnO }_{ 4 }\)
The equivalent conductances of two strong electrolytes at infinite dilution in H2O at \({ 25 }^{ \circ }C\) are given below \({ { \wedge }_{ { CH }_{ 3 }COONa }^{ \circ } }=91.0\ S\ { cm }^{ 2 }\ /\ equiv\) \({ { \wedge }_{ hci }^{ \circ } }=426.2\ S\ { cm }^{ 2 }\ /\ equiv\). What additional information/quantity one needs to calculate of an aqueous solution of acetic acid?
- (a)
\({ \wedge }^{ \circ }\ of\ NaCI\)
- (b)
\({ \wedge }^{ \circ }\ of\ { CH }_{ 3 }COOK\)
- (c)
The limiting equivalent conductance of \({ H }^{ + }\left( { \lambda }_{ { H }^{ + } }^{ \circ } \right) \)
- (d)
\({ \wedge }^{ \circ }\)of chloroacetic acid (CICH2COOH)