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AM CHEMISTRY > UNIT#09 ELECTROCHEMISTRY > Flashcards

UNIT#09 ELECTROCHEMISTRY Flashcards

1
Q

The oxidation state of carbon atom in glucose is;

A

Zero

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2
Q

In which of the following substance does sulphur exhibit its highest oxidation state;

A

SO2Cl2

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3
Q

What is the oxidation state of oxygen is KO2:

A

-1/2

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4
Q

The apparent charge on an atom of an element in a molecule or ion is called oxidation number. It may be:

A

➡Positive
➡Negative
➡Zero or Fraction

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5
Q

The apparent charge on an atom in a molecule is:

A

Oxidation Number

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6
Q

The oxidation number of oxygen atoms in OF2 and H2O2:

A

➡+2

➡-1

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7
Q

The element on the reactant side which has been reduced is:

HI + H2SO4 ➡ I2 + SO2 + H2O

A

S

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8
Q

A redox reaction is:

MnO2 + 4H+ ➡ Mn+2 + 2H2O

A

2e are added on LHS

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9
Q

In which of the following changes there is a transfer of the five electrons:

A

MnO4-1 ➡ Mn+2

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10
Q

In the reaction H2S + Cl2 ➡2HCl + S, H2S acts as:

A

Reducing Agent

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11
Q

*H + MnO4 ➡ Mn+2 + 4H2O, which one is correct about the given equation:

A

5e in LHS

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12
Q

Which of the following reactions occur at the cathode:

A

Cu+2 + 2e ➡Cu

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13
Q

In which of the following changes there is a transfer of two electrons:

A

MnO4-2 ➡ MnO2

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14
Q

The reactions taking place at anode and cathode are respectively:

A

➡Oxidation

➡Reduction

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15
Q

The electrolysis product of molten NaCl at electrodes:

A

➡Na

➡Cl2

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16
Q

During the electrolysis of aqueous KNO3, H2 is produced at the cathode instead of potassium due to;

A

The reduction potential of potassium is less than hydrogen

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17
Q

The cathodic reaction in the electrolysis of dilute H2SO4 with Pt electrodes;

A

Reduction

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18
Q

The product produced at the cathode when aqueous sodium chloride is electrolyzed:

A

H2

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19
Q

For the purification of copper, impure copper is made the _____

A

Anode

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20
Q

Cell potential depends upon:

A

➡Temeprature
➡Concentration of ions
➡Nature of electrolyte

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21
Q

When an element is in contact with 1M aqueous solution of its own ions, at 298K then the potential is called;

A

Standard Electrode Potential

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22
Q

The electric current obtained from the galvanic cell is a result of electrons being pushed forced from the negative electrode, through an external wire, to the positive electrode. The force with which these electrons move through the wire is called:

A

➡Electromotive Force

➡Cell Potential

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23
Q

Which is an incorrect statement about electrode potential?

A

➡It is the difference in potential of a cell, consisting of the particular electrode and the SHE❌
➡The potential set-up is when an electrode is in contact with one molar solution of its ions at standard conditions❌
➡The electrode potential of a single electrode can be measured directly✅

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24
Q

Which is not true about SHE

A

➡Finely divided platinum black is used as an electrode❌
➡Temperature is kept at 25°C❌
➡One molar solution of H2SO4 is used as an electrolyte✅
➡Electrode potential of any element can be calculated by comparison method❌

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25
Q

The working condition/s for SHE

A

➡1 atm pressure
➡298K Temperature
➡1M H+ solution

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26
Q

The potential of SHE is taken as zero which is a ___ value

A

Arbitrary

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27
Q

The electrochemical series is based on:

A

Hydrogen Scale

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28
Q

SHE acts as an anode when connected with the Cu electrode but acts as a cathode with the Zn electrode which is correct

A

➡Zn has less reduction potential than hydrogen and Cu more
➡Zn has high oxidizing potential than hydrogen and Cu more
➡Zn is above in electrochemical series than hydrogen and Cu below

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29
Q

If a salt bridge is removed from two half cells the emf is:

A

Dropped to zero

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30
Q

The cathode has the reduction potential:

A

More than anode

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31
Q

Al / Al+3 II Zn +2 / Zn galvanic cell, the anode is;

A

Al

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32
Q

Li has the least reduction potential in electrochemical series. Which has the highest?

A

F

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33
Q

The value of oxidation potential would be positive if it is;

A

Above SHE

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34
Q

In the oxidation number method, the final step to balance the equation is;

A

Inspection Method

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35
Q

Pure metal:

A

Does not corrode easily

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36
Q

H2 and O2 react in the presence of;

A

Pt

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37
Q

For a galvanic cell consisting of Zn and Fe dipped in their respective solutions:

A

Zn act as an anode

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38
Q

The least reactive transition metal;

A

Au

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39
Q

Elements like F2, and Cl2 lie:

A

Below Electrochemical series

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40
Q

Strongest reducing agent:

A

I-1

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41
Q

F2, Cl2, Br2 present in:

A

Below Electrochemical series

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42
Q

Which of the following is a potent reducing agent?

A

Li

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43
Q

In a galvanic cell, a salt bridge

A

An aqueous solution of KCl in gel

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44
Q

The efficiency of a fuel cell?

A

75%

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45
Q

Metals are ___?

A

Reducing Agents

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46
Q

Electrolysis of a dilute solution of NaCl results at the anode:

A

Oxygen

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47
Q

Each half-reaction in the ion-electron method is balanced by adding:

A

Both left and right-hand side

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48
Q

In metal hydrides the oxidation number of hydrogen is:

A

-1

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49
Q

The formation of ZnSO4 from blue copper sulphate solution is a spontaneous

A

Redox Reaction

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50
Q

Electrolysis is a:

A

Reduction Reaction

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51
Q

In balancing the redox equation the first thing is;

A

Write the skeleton equation

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52
Q

In electrochemical series reduction potential relates to only:

A

Standard Condition

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53
Q

In the ion-electron method, while balancing oxygen and Hydrogen atoms

A

First balance oxygen

54
Q

The sulphate ion is:

A

Tetrahedral

55
Q

Conversion of electrical energy into chemical energy is:

A

Electrochemistry

56
Q

In Al2S3, the valency of Al is:

A

3

57
Q

Which of the following is a feasible reaction?

A

Zn + HCl ➡ZnCl2 +H2

58
Q

The element present at bottom of the electrochemical series acts as:

A

➡Cathode

➡Oxidizing Agent

59
Q

The reaction which is responsible for the production of electricity in the voltaic cell is:

A

Redox

60
Q

In all oxidation reactions, the atoms of an element in a chemical species lose electrons and increase their

A

Oxidation states

61
Q

In MgCl2, the oxidation state of Cl is:

A

-1

62
Q

Which one of the following behaves as a redox reaction?

A

2Na + Cl2 ➡2NaCl

63
Q

In SO4 ^-2 the oxidation number of sulphur is:

A

+6

64
Q

Study the following redox reaction:
10Cl- + 16H+ + 2MnO4- ➡5Cl2 + 2Mn+2 + 8H2O
Which statement is true about this reaction?

A

Manganese is reduced from +7 to +2

65
Q

In NO3-¹, the oxidation number of N is:

A

+5

66
Q

The oxidation state of carbon in C2O4-² is:

A

+3

67
Q

The value of the oxidation number of chlorine in HClO3 is:

A

+5

68
Q

In a voltaic cell, a salt bridge is used in order to:

A

Allow movement of ions between two cells

69
Q

The potential difference of an electrochemical cell is measured in:

A

Voltmeter

70
Q

In an electrochemical series, elements are arranged on the basis of:

A

Hydrogen Scale

71
Q

The E value of standard copper half-cell is +0.34V, measured when it is connected with SHE. In this case, the half-reaction taking place at SHE is:

A

H2 ➡ 2H+ + 2e

72
Q

The standard electrode potential of hydrogen is arbitrarily taken at 298K is:

A

0.00 Volt

73
Q

Coinage metals Cu, Ag and Au are the least reactive because they have;

A

Positive Reduction Potential

74
Q

Study the following facts:
▶Zn ➡ Zn+2 + 2e E= +0.76 V
▶Cu ➡ Cu+2 +2e E= -0.34 V

A

Cu + Zn+2 ➡ Cu+2 + Zn

75
Q

Keeping in mind the electrode potential, which one o the following reaction is feasible?

A

Fe + CuSO4 ➡FeSO4 + Cu

76
Q

Stronger is the oxidizing agent is the :

A

Reduction Potential

77
Q

Which of the following metal does not liberate hydrogen on reaction with acid?

A

Pt

78
Q

Which one of the following elements is the strongest reducing agent?

A

Sodium

79
Q

Rusting of iron metal Fe occurs when Fe gets converted into Fe2O3. What happens with Fe?

A

Fe is oxidized

80
Q

During space flights, astronauts obtained water from:

A

Fuel Cell

81
Q

The electrolyte used in a fuel cell is;

A

KOH

82
Q

In which of the following reactions does hydrogen acts as an oxidizing agent:

A

2Na + H2 ➡ 2NaH

83
Q

Choose the true statement regarding the reaction given below:
2Na + Cl2 ➡2NaCl

A

Chlorine acts as an oxidizing agent and sodium as a reducing agent

84
Q

A cell is constructed of the following two half cells. What is the E+ of the cell?
Ag+ + e- ➡Ag Eo = +0.80V
Al+3 + e- ➡Al Eo = -1.67V

A

2.47 V

85
Q

Which of the following is the spontaneous reaction?

A

▶Zn + Cu+2 ➡ Zn+2 + Cu

The electrode potential is Positive

86
Q

When a zinc electrode is coupled with a copper electrode in a galvanic cell?

A

Reduction takes place at the copper electrode

87
Q

The oxidation state of nitrogen in NH4NO3 is:

A

-3 and 5

88
Q

The oxidation state of “S” in the (S2O3)-2 is:

A

+2

89
Q

The common oxidation number of halogens are;

A

-1

90
Q

During the oxidation process, the oxidation number of an element;

A

Increases

91
Q

The oxidation state of chlorine in ClF is:

A

+1

92
Q

The oxidation number of “P” in PO4^-3

A

+5

93
Q

To balance oxygen in ion electron method in acidic medium, we add:

A

H2O

94
Q

In fuel cell, N2H4 reacts with N2H4 + O2 ➡N2 + 2H2O. The number of electrons lost by each nitrogen atom will be;

A

2

95
Q

In the reaction

2Fe + 3Cl2 ➡2FeCl3

A

Fe is oxidized

96
Q

Which is true about the reaction Mg + Cl2➡MgCl2

A

Mg is oxidized

97
Q

Electrochemistry is concerned with the:

A

➡Nelson cell
➡Voltaic Cell
➡Hg-Cell

98
Q

Which of the following has a non-spontaneous oxidation-reduction reaction?

A

Electrolytic Cell

99
Q

The electrolytic products of which of the following are same as for the electrolysis of water.

A

Aqueous ZnSO4

100
Q

Which of the following factors accounts for degree of dissociation of an electrolyte:

A

➡Nature of Electrolyte
➡Temperature
➡Concentration

101
Q

List of elements based on hydrogen scale is called:

A

Electrochemical Series

102
Q

The element that act as anode always have ____ position in electrochemical series:

A

Higher

103
Q

For electrochemical cell Zn/ZnSO4 (1 M) || Fe2(SO4)3 (1M) /Fe, the number of electrons involved in balanced equation are;

A

6

104
Q

The standard electrode potential is measured by:

A

Voltmeter

105
Q

Aluminium displaces hydrogen from dilute HCl whereas silver does not. The e.m.f of a cell prepared by combining Al /Al+3 and Ag/Ag+ is 2.46V. The reduction potential of silver electrode is +0.80V. The Eo (red) of aluminium electrode is:

A

-1.66 V

106
Q

If Cu(NO302 is electrolyzed in presence of an inert electrode, product at cathode and at anode respectively:

A

➡Cu

➡O2

107
Q

Metal that deposits at cathode when aqueous solution of its salt is electrolyzed:

A

Cu

108
Q

Group 1 metals are -__ reactive than group 2 metals

A

More

109
Q

If a strip of Cu metal is placed in a solution of FeSO4 then,

A

No reaction takes place

reduction potential of Cu is higher than Fe

110
Q

The oxidation no. of Cr is ____ in K2Cr2O7 or K2CrO4.

A

+6

111
Q

In which of the following compound oxygen show -1 oxidation state:

A

Na2O2

112
Q

The oxidation no. of Mn in [MnO4]-2 is:

A

+6

113
Q

The oxidation numebr of oxygen atom in OF2 and H2O2:

A

+2, -1

114
Q

How many electrons are required to balance the following half reaction:
2H2O + [MnO4]-1 ➡ MnO2 + [OH]-1

A

3e on left side

115
Q

Which of the following is not a redox reaction?

A

BaCl2 + H2SO4 ➡BaSO4 +2HCl

116
Q

During balancing of Redox equations by oxidation number method the ‘O’ and H atoms are balanced by:

A

Inspection Method

117
Q

In the electrolysis of dil. H2SO4 using platinum electrode, what is true:

A

Oxygen is evolved at anode

(At anode, [OH]-1 is oxidized to O2 due to higher oxidation potential to sulphate ions

118
Q

During the electrolysis of Brine solution, the gas liberated at the cathode is;

A

H2

119
Q

The products of electrolysis of dilute aqueous sodium nitrate are:

A

➡H2

➡O2

120
Q

The products of electrolysis will not be same in the case of:

A

CuSO4

121
Q

Which of the following has a spontaneous oxidation-reduction reaction?

A

➡Galvanic Cell

➡Voltaic Cell

122
Q

Standard electrode potential is measured at;

A

1 atm, 25°C, 1.0M

123
Q

Electrode potential of an element can be calculated by comparing it with;

A

SHE

124
Q

The standard reduction potential of Zn is;

A

-0.76

125
Q

The conductivity of strong electrolyte:

A

Does no change considerably on dilution

126
Q

Select the correct statement about salt bridge:

A

Maintain its neutrality

127
Q

Standard electrode potential of a metal depends upon

A

➡Temeprature
➡Molarity of the ions in solution
➡Nature of metal

128
Q

Which of the followign value of standard reduction potential suggest that the reducing power of an element is approximately equal o oxidizing power

A

0.00 V

129
Q

If reduction potentials of different metals are:
A= -0.25V, B= -1.0V, C=-1.50V, D=-1.27V
Which can displace all others from their salts:

A

C

130
Q

Which reaction is not possible:

A

Zn + MgSO4 ➡ ZnSO4 + Mg

131
Q

___ can displace hydrogen from acid more easily:

A

Ca

AM CHEMISTRY (19 decks)

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