Chemistry - Electrochemistry
Exam Duration: 45 Mins Total Questions : 30
When an aqueous solution of sulphuric acid is electrolysed using platinum electrodes, the products of electrolysis are
- (a)
hydrogen and oxygen
- (b)
hydrogen and hydroxyl ion
- (c)
hydrogen and sulphate ion
- (d)
oxygen and sulphate ion
The products obtained at the electrodes by the electrolysis of copper sulphate solution using copper electrodes are
- (a)
Cu and SO42-
- (b)
OH- and H2
- (c)
O2 and H2
- (d)
NONE OF THESE
Electrochemical reaction at the anode is oxidation.Which one of the following is not an anodic reaction?
- (a)
\(Cl\longrightarrow Cl+e\)
- (b)
\(Fe^{3+}+e^-\longrightarrow Fe^{2+}\)
- (c)
\(Cu\longrightarrow cu^{2+} +2e\)
- (d)
\(Zn=Zn^{2+} 2e^-\)
Cells containing a solution of mercuric perchlorate(i),mercury nitrate (ii),and mercurous perchlorate(iii),were connected ,in series so that the same quantity of electrocity passes through them,The amount of mercury obtained at the cathode is the same
- (a)
in all the cells
- (b)
in cells(i) and (ii) but more in cell(iii)
- (c)
in cells(i) and (iii) but more in cell(ii)
- (d)
in cells(ii) and (iii) but more in cell(i)
Suppose one mole of electrons is passed through three electrolytes in series,containing silver,zinc and ferric ions.Assuming that the cathodic reaction in such cell reduces the cations to the metal,moles of each metal obtained is
- (a)
1 mol Ag,1 mol Zn,1 mol Fe
- (b)
0.5 mol Ag,0.5 mol Zn,1 mol Fe
- (c)
1 mol Ag,0.5 mol Zn,0.33 mol Fe
- (d)
0.5 mol Ag,1 mol Zn,0.33 mol Fe
A current liberates 0.504g of hydrogen in 2 hours.How many grams of copper can be liberated by the same current flowing for the same time in cuprous cyanide solution?
- (a)
12.7
- (b)
15.9
- (c)
31.8
- (d)
63.6
From an electric wire \(1.27\times 10^{18} \) electrons are transferred per minute.The current in A that would be flowing per second is
- (a)
\(3.39\times10^{-3} A\)
- (b)
\(3.89\times10^{-3} A\)
- (c)
\(3.09\times10^{-3} A\)
- (d)
\(3.38\times10^{-3} A\)
Which of the following reactions is anodic?
- (a)
\(2OH^{-}\longrightarrow H_2O+1/2O_2+2e\)
- (b)
\(H^+ +e\longrightarrow 1/2H_2\)
- (c)
\(Fe^{3+}\longrightarrow Fe^{2+}-e\)
- (d)
\(2H_2O+2e\longrightarrow H_2+OH^{-}\)
A solution containing one mole \(l^{-1}\) each of \(Cu(NO_3)_2,AgNO_3,Hg_2(NO_3)_2 \) and \(Mg(NO_3)_2\) is electrolysed using inert electrodes.\(E^o\) in volt are: with increasing voltage,the sequence of deposition of metals on the cathode will be
- (a)
Ag,Hg,Cu,Mg
- (b)
Mg,Cu,Hg,Ag
- (c)
Ag,Hg,Cu
- (d)
Cu,Hg,Ag
The approximate mass of copper deposited on the cathode when a current of 0.2 ampere is passed through a solution of copper sulphate for 10 minutes.E copper=31.78
- (a)
0.04g
- (b)
0.03g
- (c)
0.02g
- (d)
0.01g
The time required in seconds to coat a metal surface of 80cm2 with a 0.005mm thick layer by passing a current of 3 ampere is
- (a)
100s
- (b)
125s
- (c)
1200s
- (d)
150s
A certain current liberated 0.504g of hydrogen in 2 hours.The approximate amount of copper deposited in grams by the same current flowing for the same time in a CuSO4 solution:
- (a)
10 g
- (b)
12 g
- (c)
14 g
- (d)
16 g
Three Faraday of electricity is passed through aqueous solution of AgNO3,NiSO4,CrCl3 kept in three vessels using inert electrodes .The ratio in moles in which the metals Ag,Ni,Cr will be deposited :
- (a)
2:3:6
- (b)
6:3:2
- (c)
3:2:1
- (d)
1:2:3
The quantity of electricity required required to reduce 12.3g of nitrobenzene to aniline asuming 50% current efficiency is
- (a)
57900 C
- (b)
28950 C
- (c)
115800 C
- (d)
231600 C
How many coulombs of electricity are required to reduce 1 mol of MnO-4 to Mn2+?
- (a)
\(4.825\times10^5 c\)
- (b)
\(8.825\times10^5 c\)
- (c)
\(12.825\times10^5 c\)
- (d)
NONE OF THE ABOVE
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
For the cell Mg(s)|Mg2+||Ag+(aq)|Ag(s) the value of E0 cell is3.17 v .The value of equlibrium constant for this cell is of the order of
- (a)
1037
- (b)
1032
- (c)
10100
- (d)
10107
The e.m.f of the cell formed by E0 Fe2+/Fe=-0.45 v would be approximately
- (a)
0.25 v
- (b)
0.22 v
- (c)
0.26 v
- (d)
None of the above
What will be the emf for the given cell? Pt|H2(P1)|H+ (aq) || H2(P2) Pt
- (a)
\(\frac{RT}{F} log \frac{P_1}{p_2}\)
- (b)
\(\frac{RT}{2F} log \frac{P_1}{p_2}\)
- (c)
\(\frac{RT}{P} log \frac{P_1}{p_2}\)
- (d)
NONE OF THESE
The reaction 1/2H2(g)+AgCl(s)\(\longrightarrow \) H+(aq)+Cl-(aq)+Ag(s) occurs in the galvanic cell
- (a)
Ag/AgCl(s) KCl soln//AgNo3(aq)/Ag
- (b)
Pt/H2(g) HCl soln //AgNO3(aq)/Ag
- (c)
Pt/H2(g) HCl soln//AgCl(s)/Ag
- (d)
Pt/H2(g) KCl soln//AgCl(s)/Ag
Given:\(\lambda^{\infty}_+(\frac{1}{2}Fe^{3+})=68 ohm^{-1} cm^2 mol^{-1}\) \(\lambda^{\infty}_+(\frac{1}{2}SO^{2-}_4)=80 ohm^{-1} cm^2 mol^{-1}\) the \(\lambda ^{\infty}_m\) of \(Fe_2(SO_3)_3 \) would be
- (a)
408 ohm-1 cm2 mol-1
- (b)
480ohm-1 cm2 mol-1
- (c)
888 ohm-1 cm2 mol-1
- (d)
None of the above
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
Which cell will measure standard electrode potential of copper electrode?
- (a)
\(Pt(s)\ |{ H }_{ 2 }(g,\ 0.1\ bar)|\ { H }^{ + }(aq,\ 1M)\ ||\ { Cu }^{ 2+ }(aq,\ 1\ M)\ |\ Cu\)
- (b)
\(Pt(s)\ |{ H }_{ 2 }(g,\ 1\ bar)|\ { H }^{ + }(aq,\ 1M)\ ||\ { Cu }^{ 2+ }(aq,\ 2\ M)\ |\ Cu\)
- (c)
\(Pt(s)\ |{ H }_{ 2 }(g,\ 1\ bar)|\ { H }^{ + }(aq,\ 1M)\ ||\ { Cu }^{ 2+ }(aq,\ 1\ M)\ |\ Cu\)
- (d)
\(Pt(s)\ |{ H }_{ 2 }(g,\ 1\ bar)|\ { H }^{ + }(aq,\ 0.1M)\ ||\ { Cu }^{ 2+ }(aq,\ 1\ M)\ |\ Cu\)
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 standard emf of a cell involving one electron change is found to be 0.591 V at \({ 25 }^{ \circ }C\). The equilibrium constant of the reaction is (F=96500 C mol-1)
- (a)
1.0 \(\times\) 101
- (b)
1.0 \(\times\) 105
- (c)
1.0 \(\times\) 1010
- (d)
1.0 \(\times\) 1030
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
Using the standard electrode potential, find out the pair between which redox reaction is no feasible. \({ E }^{ \circleddash }\) values: Fe3+ / Fe2+ = +0.77, I2 / I = +0.54 V. Cu2+ = +0.34, Ag+/Ag = +80 V.
- (a)
Fe3+ and I-
- (b)
Ag+ and Cu
- (c)
Fe3+ and Cu
- (d)
Ag+ and Fe3+
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 reduction potential of hydrogen half-cell will be negative if
- (a)
p(H2) = 1 atm and [H+] = 2.0 M
- (b)
p(H2) = 1 atm and [H+] = 1.0 M
- (c)
p(H2) = 2 atm and [H+] = 1.0 M
- (d)
p(H2) = 2 atm and [H+] = 2.0 M
For the redox reaction, \(Zn(s)+C{ u }^{ 2+ }(0.1M)\longrightarrow { Zn }^{ 2+ }(1M)+Cu(s)\) taking place in a cell, \({ E }^o_{ cell }\) is 1.10 v. \({ E }_{ cell }\) for the cell will be \(\left( 2.303\frac { RT }{ F } =0.0591 \right) \)
- (a)
2.14 V
- (b)
1.80 V
- (c)
1.07 V
- (d)
0.82 V
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