electrochem

Question 1

What is oxidation?

Answer 1

The process where an atom or ion loses one or more electrons.

Question 2

What is reduction?

Answer 2

The process where an atom or ion gains one or more electrons.

Question 3

What is an oxidizing agent?

Answer 3

A substance that accepts electrons from another substance.

Question 4

What is a reducing agent?

Answer 4

A substance that donates electrons to another substance.

Question 5

What is the oxidation number of an atom in its elemental form?

Answer 5

Zero.

Question 6

What is the oxidation number of oxygen in peroxides?

Answer 6

-1

Question 7

What is the oxidation number of sulfur in H₂SO₄?

Answer 7

6

Question 8

How do you calculate the oxidation number of an ion?

Answer 8

Equal to the charge of the ion.

Question 9

What are the methods to balance redox reactions?

Answer 9

Oxidation number method and ion-electron method.

Question 10

What is electrolytic conduction?

Answer 10

Conduction of electricity through an electrolyte leading to a chemical reaction.

Question 11

What is molar conductivity?

Answer 11

The conductivity of a solution divided by the molar concentration of the electrolyte.

Question 12

How does dilution affect molar conductivity?

Answer 12

Dilution increases molar conductivity by allowing ions to move more freely.

Question 13

What is the difference between electrolytic and galvanic cells?

Answer 13

Electrolytic cells use electrical energy to drive a non-spontaneous reaction, while galvanic cells generate electrical energy from a spontaneous reaction.

Question 14

What is Faraday’s first law of electrolysis?

Answer 14

The amount of substance deposited or liberated at an electrode is proportional to the electric charge passed.

Question 15

What is Faraday’s second law of electrolysis?

Answer 15

The mass of a substance deposited or liberated at an electrode is proportional to its equivalent weight.

Question 16

What is standard electrode potential?

Answer 16

The voltage developed by an electrode in a half-cell under standard conditions.

Question 17

What is the standard hydrogen electrode (SHE)?

Answer 17

A reference electrode used to measure the electrode potentials of other half-cells, with a potential of 0 V.

Question 18

What is the electrochemical series?

Answer 18

A list of elements arranged in order of their standard electrode potentials.

Question 19

How does concentration affect electrode potential?

Answer 19

According to the Nernst equation, electrode potential is influenced by the concentration of ions.

Question 20

What is the Nernst equation?

Answer 20

The equation that relates the electrode potential to the concentration of ions in the redox reaction.

Question 21

What is the relationship between emf and Gibbs energy change?

Answer 21

ΔG = -nFE, where ΔG is the Gibbs free energy change, n is the number of electrons, F is Faraday’s constant, and E is the emf.

Question 22

What is the effect of dilution on the conductivity of an electrolyte?

Answer 22

Dilution decreases the conductivity as the ions become further apart, reducing their ability to carry current.

Question 23

What is the relationship between current and voltage in an electrolytic cell?

Answer 23

The current is directly proportional to the voltage applied across the cell.

Question 24

What is the purpose of the electrolyte in an electrolytic cell?

Answer 24

The electrolyte provides ions that can move and carry charge, completing the electrical circuit.

Question 25

What is the role of electrodes in an electrolytic cell?

Answer 25

Electrodes serve as surfaces for the oxidation and reduction reactions during electrolysis.

Question 26

What is the difference between primary and secondary batteries?

Answer 26

Primary batteries are non-rechargeable, while secondary batteries can be recharged and used multiple times.

Question 27

What is a salt bridge in a galvanic cell?

Answer 27

A salt bridge maintains electrical neutrality by allowing the flow of ions between two half-cells.

Question 28

What is the function of a voltmeter in an electrochemical cell?

Answer 28

A voltmeter measures the electric potential (voltage) between two electrodes in a cell.

Question 29

How do you calculate the cell potential of a galvanic cell?

Answer 29

Cell potential is calculated as the difference between the reduction potentials of the cathode and anode.

Question 30

What does a positive electrode potential indicate?

Answer 30

A positive electrode potential indicates that a species is more likely to be reduced.

Question 31

What does a negative electrode potential indicate?

Answer 31

A negative electrode potential indicates that a species is more likely to be oxidized.

Question 32

What is the effect of temperature on electrode potential?

Answer 32

Temperature can influence the electrode potential by altering the kinetic energy of ions and the equilibrium of redox reactions.

Question 33

What is the significance of a standard electrode potential of 0 V?

Answer 33

The standard electrode potential of 0 V is assigned to the standard hydrogen electrode (SHE), which is used as a reference.

Question 34

How do you predict the products of electrolysis?

Answer 34

The products of electrolysis depend on the type of electrolyte, the electrode materials, and the voltage applied.

Question 35

What is the relationship between the Gibbs free energy and the emf of a cell?

Answer 35

ΔG = -nFE, where ΔG is Gibbs free energy, n is the number of moles of electrons, F is Faraday's constant, and E is the emf.

Question 36

What is the Nernst equation used for?

Answer 36

The Nernst equation is used to calculate the electrode potential at non-standard conditions.

Question 37

What is the effect of concentration on electrode potential?

Answer 37

The concentration of ions in solution influences the electrode potential, as described by the Nernst equation.

Question 38

What is the significance of the electrochemical series?

Answer 38

The electrochemical series helps in predicting the direction of redox reactions and determining the standard electrode potentials.

Question 39

What is a galvanic cell?

Answer 39

A galvanic cell is a device that generates electrical energy from spontaneous chemical reactions.

Question 40

What is the role of the anode in an electrolytic cell?

Answer 40

The anode is the electrode where oxidation occurs in an electrolytic cell.

Question 41

What is the role of the cathode in an electrolytic cell?

Answer 41

The cathode is the electrode where reduction occurs in an electrolytic cell.

Question 42

What is the Nernst equation used for in numerical problems?

Answer 42

To calculate the electrode potential at non-standard conditions using ion concentrations.

Question 43

How do you calculate the electrode potential using the Nernst equation?

Answer 43

E = E° - (0.0591/n) log [products/reactants], where n is the number of electrons transferred.

Question 44

How does increasing ion concentration affect electrode potential?

Answer 44

Increasing ion concentration of the reduced species increases the electrode potential.

Question 45

How does decreasing ion concentration affect electrode potential?

Answer 45

Decreasing ion concentration of the reduced species decreases the electrode potential.

Question 46

Predict the electrolysis product of molten NaCl.

Answer 46

At cathode: Na(s), at anode: Cl₂(g).

Question 47

Predict the electrolysis product of aqueous NaCl.

Answer 47

At cathode: H₂(g), at anode: Cl₂(g), as water is preferentially reduced.

Question 48

Predict the electrolysis product of CuSO₄ solution with copper electrodes.

Answer 48

At cathode: Cu(s) deposition, at anode: Cu dissolves as Cu²⁺.

Question 49

Predict the electrolysis product of CuSO₄ solution with platinum electrodes.

Answer 49

At cathode: Cu(s) deposition, at anode: O₂(g) from water oxidation.

Question 50

What is the relationship between Gibbs free energy and equilibrium constant?

Answer 50

ΔG° = -RT ln K, where K is the equilibrium constant.

Question 51

How can the standard emf of a cell be used to determine its spontaneity?

Answer 51

If E°cell > 0, the reaction is spontaneous; if E°cell < 0, the reaction is non-spontaneous.

Question 52

How does temperature affect the Nernst equation?

Answer 52

Temperature changes the value of electrode potential by affecting reaction equilibrium.

Question 53

What is an application of electrolysis in industry?

Answer 53

Production of aluminum from bauxite using the Hall-Héroult process.

Question 54

What is an example of corrosion as a redox reaction?

Answer 54

Rusting of iron: Fe oxidizes to Fe²⁺ and further to Fe₃O₄ in presence of water and oxygen.

Question 55

How can electrochemical principles be used to prevent corrosion?

Answer 55

Cathodic protection using sacrificial anodes like Zn or Mg.

Question 56

What is a fuel cell?

Answer 56

An electrochemical device that converts chemical energy from fuel into electricity.

Question 57

What is the main reaction in a hydrogen fuel cell?

Answer 57

2H₂ + O₂ → 2H₂O + energy, producing electrical power.

Question 58

What is the significance of standard hydrogen electrode in electrochemistry?

Answer 58

It is used as a reference electrode with a defined potential of 0V.

Question 59

What is the Faraday constant and its value?

Answer 59

The charge carried by 1 mole of electrons, approximately 96485 C/mol.

Question 60

What is the unit of conductivity in SI units?

Answer 60

Siemens per meter (S/m).

Question 61

How does the number of electrons transferred affect the Nernst equation?

Answer 61

Higher n values make electrode potential less sensitive to concentration changes.