UNIT#09 ELECTROCHEMISTRY Flashcards by Dr. Xainter

The oxidation state of carbon atom in glucose is;

Zero

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

SO2Cl2

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What is the oxidation state of oxygen is KO2:

-1/2

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

➡Positive
➡Negative
➡Zero or Fraction

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The apparent charge on an atom in a molecule is:

Oxidation Number

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The oxidation number of oxygen atoms in OF2 and H2O2:

➡+2

➡-1

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

HI + H2SO4 ➡ I2 + SO2 + H2O

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A redox reaction is:

MnO2 + 4H+ ➡ Mn+2 + 2H2O

2e are added on LHS

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

MnO4-1 ➡ Mn+2

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

Reducing Agent

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

5e in LHS

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Which of the following reactions occur at the cathode:

Cu+2 + 2e ➡Cu

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

MnO4-2 ➡ MnO2

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The reactions taking place at anode and cathode are respectively:

➡Oxidation

➡Reduction

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The electrolysis product of molten NaCl at electrodes:

➡Na

➡Cl2

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

The reduction potential of potassium is less than hydrogen

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

Reduction

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

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

Anode

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Cell potential depends upon:

➡Temeprature
➡Concentration of ions
➡Nature of electrolyte

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

Standard Electrode Potential

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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:

➡Electromotive Force

➡Cell Potential

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Which is an incorrect statement about electrode potential?

➡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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Which is not true about SHE

➡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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The working condition/s for SHE

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

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

Arbitrary

The electrochemical series is based on:

Hydrogen Scale

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

➡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

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

Dropped to zero

The cathode has the reduction potential:

More than anode

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

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

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

Above SHE

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

Inspection Method

Pure metal:

Does not corrode easily

H2 and O2 react in the presence of;

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

Zn act as an anode

The least reactive transition metal;

Elements like F2, and Cl2 lie:

Below Electrochemical series

Strongest reducing agent:

I-1

F2, Cl2, Br2 present in:

Below Electrochemical series

Which of the following is a potent reducing agent?

In a galvanic cell, a salt bridge

An aqueous solution of KCl in gel

The efficiency of a fuel cell?

75%

Metals are ___?

Reducing Agents

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

Oxygen

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

Both left and right-hand side

In metal hydrides the oxidation number of hydrogen is:

-1

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

Redox Reaction

Electrolysis is a:

Reduction Reaction

In balancing the redox equation the first thing is;

Write the skeleton equation

In electrochemical series reduction potential relates to only:

Standard Condition

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

First balance oxygen

The sulphate ion is:

Tetrahedral

Conversion of electrical energy into chemical energy is:

Electrochemistry

In Al2S3, the valency of Al is:

Which of the following is a feasible reaction?

Zn + HCl ➡ZnCl2 +H2

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

➡Cathode | ➡Oxidizing Agent

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

Redox

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

Oxidation states

In MgCl2, the oxidation state of Cl is:

-1

Which one of the following behaves as a redox reaction?

2Na + Cl2 ➡2NaCl

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

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

Manganese is reduced from +7 to +2

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

The oxidation state of carbon in C2O4-² is:

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

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

Allow movement of ions between two cells

The potential difference of an electrochemical cell is measured in:

Voltmeter

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

Hydrogen Scale

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:

H2 ➡ 2H+ + 2e

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

0.00 Volt

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

Positive Reduction Potential

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

Cu + Zn+2 ➡ Cu+2 + Zn

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

Fe + CuSO4 ➡FeSO4 + Cu

Stronger is the oxidizing agent is the :

Reduction Potential

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

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

Sodium

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

Fe is oxidized

During space flights, astronauts obtained water from:

Fuel Cell

The electrolyte used in a fuel cell is;

KOH

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

2Na + H2 ➡ 2NaH

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

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

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

2.47 V

Which of the following is the spontaneous reaction?

▶Zn + Cu+2 ➡ Zn+2 + Cu | The electrode potential is Positive

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

Reduction takes place at the copper electrode

The oxidation state of nitrogen in NH4NO3 is:

-3 and 5

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

The common oxidation number of halogens are;

-1

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

Increases

The oxidation state of chlorine in ClF is:

The oxidation number of "P" in PO4^-3

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

H2O

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

In the reaction | 2Fe + 3Cl2 ➡2FeCl3

Fe is oxidized

Which is true about the reaction Mg + Cl2➡MgCl2

Mg is oxidized

Electrochemistry is concerned with the:

➡Nelson cell ➡Voltaic Cell ➡Hg-Cell

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

Electrolytic Cell

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

Aqueous ZnSO4

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

➡Nature of Electrolyte ➡Temperature ➡Concentration

List of elements based on hydrogen scale is called:

Electrochemical Series

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

Higher

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

The standard electrode potential is measured by:

Voltmeter

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:

-1.66 V

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

➡Cu | ➡O2

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

Group 1 metals are -__ reactive than group 2 metals

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

No reaction takes place | reduction potential of Cu is higher than Fe

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

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

Na2O2

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

The oxidation numebr of oxygen atom in OF2 and H2O2:

+2, -1

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

3e on left side

Which of the following is not a redox reaction?

BaCl2 + H2SO4 ➡BaSO4 +2HCl

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

Inspection Method

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

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

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

The products of electrolysis of dilute aqueous sodium nitrate are:

➡H2 | ➡O2

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

CuSO4

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

➡Galvanic Cell | ➡Voltaic Cell

Standard electrode potential is measured at;

1 atm, 25°C, 1.0M

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

SHE

The standard reduction potential of Zn is;

-0.76

The conductivity of strong electrolyte:

Does no change considerably on dilution

Select the correct statement about salt bridge:

Maintain its neutrality

Standard electrode potential of a metal depends upon

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

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

0.00 V

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:

Which reaction is not possible:

Zn + MgSO4 ➡ ZnSO4 + Mg

___ can displace hydrogen from acid more easily:

UNIT#09 ELECTROCHEMISTRY Flashcards

(131 cards)