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Trackspec 3 > 02 Electrochemistry and Corrosion > Flashcards

02 Electrochemistry and Corrosion Flashcards

1
Q

electrochemical cell

A

An _____________ is a device that can generate electrical energy from the chemical reactions occurring in it, or use the electrical energy supplied to it to facilitate chemical reactions in it. These devices are capable of converting chemical energy into electrical energy, or vice versa.

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2
Q

galvanic cell; electrolytic cell

A

A ____________ converts chemical energy into electrical energy; while ____________ electrical energy into chemical energy

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3
Q

loss

gain

A

Oxidation is ______ of e-

Reduction is ______ of e-

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4
Q

galvanic cell; electrolytic cell

A

Spontaneous redox reaction: _______________

Nonspontaneous redox reaction: _______________

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5
Q

water

A

The presence of ______________ is necessary in order to transport ions to and from the metal, but a thin film of adsorbed moisture can be sufficient.

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6
Q

Galvanic Corrosion

A

Also called “dissimilar metal corrosion” or wrongly “electrolysis”) refers to corrosion damage induced when two dissimilar materials are coupled in a corrosive electrolyte.

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7
Q

less; more

A

In a bimetallic couple, the __________ noble material becomes the anode and tends to corrode at an accelerated rate, compared with the uncoupled condition and the __________ noble material will act as the cathode in the corrosion cell

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8
Q

Luigi Galvani

A

Late 18th century- The bimetallic driving force was discovered through as series of experiments with the exposed muscles and nerves of a frog that contracted when connected to a bimetallic conductor.

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9
Q

Alessandro Volta

A

1800- the principle was later put into a practical application by first electrical cell, or battery: a series of metal disks of two kinds, separated by cardboard disks soaked with acid or salt solutions.

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10
Q

Sir Humphry Davy

A

Early 19th century- The principle was also engineered into the useful protection of metallic structures.

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11
Q

Electrolyte

A

A conductive solution, like saltwater or even tap water, that allows the flow of ions between the anode and cathode.

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12
Q

Electrical connection

A

A metallic pathway connecting the anode and cathode, allowing the flow of electrons to complete the circuit.

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13
Q

anode; cathode

A

Less noble: _____________; more noble: _____________.

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14
Q

sacrificial anode

A

Introducing a more active metal, called a ________________, can be strategically placed to corrode preferentially and protect the desired metal. This principle is used in cathodic protection systems for pipelines and other structures.

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15
Q

coatings

A

Applying protective _____________ to the anode can create a barrier and impede its interaction with the electrolyte.

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16
Q

Electrode Potential

A

It is the tendency for an electrode to lose or gain electrons when dipped in the solution of its ions.

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17
Q

1 atm; 298 K; 1 M

A

Standard Electrode Potential is measured at _____ atm, _____ K, and _____ M.

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18
Q

two

A

Zinc atoms in the rod undergo oxidation by losing _____ electrons to form zinc ions which go into the solution

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19
Q

-0.76

A

The reduction potential of zinc electrode is ____________, which implies that ZINC is more electropositive than hydrogen

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20
Q

0.34

A

The reduction potential of zinc electrode is ____________, which implies that COPPER is more electropositive than hydrogen

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21
Q

anode to cathode

A

Electrons always flow from __________ to __________.

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22
Q

Current

A

_____________ is produced in an electrochemical cell while corrosion is occurring.

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23
Q

Electrochemical corrosion

A

_______________ involves the transfer of electrons from the anode to the cathode.

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24
Q

Corrosion rate

A

This is the speed at which any given metal deteriorates in a specific environment.

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25
Q

instantaneous

A

Electrochemical corrosion rate is “________________.”

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26
Q

number of coulombs

A

Faraday developed the ________________ known as “FARADAY”

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27
Q

Faraday’s First Law of Electrolysis

A

This law states that: Amount of substance produced at each electrode is directly proportional to the charge flowing through the cell.

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28
Q

electro-chemical equivalent

A

In Faraday’s First Law of Electrolysis, z is a constant, and known as ______________, and is characteristic of the substance deposited.

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29
Q

Mass of Oxidized Metal

A

This is the formula for _________________ under Faraday’s First Law of Electrolysis.

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30
Q

Corrosion Rate

A

This is the formula for _________________ under Faraday’s First Law of Electrolysis.

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31
Q

Electrochemical Process

A

It is defined as a chemical reaction involving the transfer of electrons between two electrodes in an electrochemical cell.

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32
Q

Luigi Galvani

A

The galvanic cell is named after _____________, a physician in Bologna, Italy, who published his studies of electrochemical action in 1791.

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33
Q

electrochemical cells

A

It is a device that converts chemical energy produced in a redox reaction into electrical energy

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34
Q

half-cells

A

Electrochemical cell is composed of two compartments or _______________, each composed of an electrode dipped in a solution of electrolyte.

35
Q

positive to negative

A

On short-circuiting such a cell (attaching a low - resistance wire to connect the two electrodes), positive current flows through the metallic path from ___________ electrode to ___________ electrode.

36
Q

negative to positive

A

Electrons, of course, go from ___________ to ___________ pole, opposite to the imaginary flow of positive carriers.

37
Q

Anode

A

Denoted by a negative sign that releases electrons to the external circuit and oxidizes during an electrochemical reaction.

38
Q

Cathode

A

Denoted by a positive sign that acquires electrons from the external circuit and is reduced during the electrochemical reaction.

39
Q

Salt Bridge

A

It is a device used in an electrochemical cell for connecting its oxidation and reduction half cells wherein an inert electrolyte is used. It is a junction that connects the anodic and cathodic compartments in a cell or electrolytic solution.

40
Q

Electrolytes

A

It is the medium that provides the ion transport mechanism between the cathode and anode of a cell. They are often thought of as liquids, such as water or other solvents, with dissolved salts, acids, or alkalis that are required for ionic conduction.

41
Q

Standard Reduction Potential

A

It lists elements and compounds in terms of how strongly they desire to pull electrons, therefore the higher you go up here, the more these elements want to attract electrons towards them.

42
Q

electrochemical cell

A

It is a container in which chemical reactions produce electricity, or an electric current produces chemical change.

43
Q

electrolytic cell

A

Use electricity to force electrons to move between atoms to make oxidation-reduction reactions happen

44
Q

electrochemical cell;

electrolytic cell

A

ΔG < 0: _______________

ΔG ≥ 0: _______________

45
Q

Dissimilar Electrode Cell

A

These cells involve different types of metals or metal compositions coming into contact, leading to electron transfer between them.

46
Q

Salt concentration cell

A

These are cells with two identical electrodes, each in contact with a solution of different composition.

47
Q

Differential Aeration Cell

A

Part of the metal exposed to air is more oxygenated and acts as a Cathode. Part of the metal immersed in the electrolyte is poorly oxygenated & acts as an anode.

48
Q

Differential Temperature Cell

A

This is the type of cell when two identical electrodes are immersed in same electrolyte, but the electrodes are immersed into solution of two different temperatures.

49
Q

emf Series

A

The __________ is an orderly arrangement of the standard potentials for all metals. The more negative values correspond to the more reactive metals.

50
Q

Galvanic Cell

A

It arises when two metals with dissimilar compositions come into contact in the presence of an electrolyte.

51
Q

Galvanic Series

A

Determines the electrochemical potential and nobility of metals (and metal alloys). Ranking of metals and alloys according to their free corrosion potential in a given electrolyte.

52
Q

Voltmeter

A

Used to measure potential differences.

53
Q

platinum

A

The reaction of SHE generally takes place on a ___________ electrode.

54
Q

Calomel Reference Electrode

A

Pure mercury is placed at the bottom of the tube, which is covered with a paste of mercury- mercurous chloride (Hg+ Hg2Cl2).

55
Q

Silver-Silver Chloride Reference Electrode

A

Composed of a silver wire, sometimes coated with a layer of solid silver chloride, immersed in a solution that is saturated with potassium chloride and silver chloride.

56
Q

Saturated Copper-Copper Sulfate Reference Electrode

A

Consists of metallic copper immersed in saturated copper sulfate. It is used primarily in field measurements where the electrode must be resistant to shock and where its usual large size minimizes polarization errors.

57
Q

Faraday’s empirical laws of electrolysis

A

These relate the current of an electrochemical reaction to the number of moles of the element being reacted and the number of moles of electrons involved.

58
Q

96,485 C/mol of electrons

A

1 Faraday is equal to:

59
Q

F∆Nn

A

Faraday’s Law can be expressed as:

60
Q

electric current

A

This is an equation for charge Q that is defined in terms of ____________.

61
Q

Corrosion current

A

It is the current produced in an electrochemical cell during corrosion. It is the dissolution current at the corrosion potential.

62
Q

Corrosion rate

A

It is the speed at which any given metal deteriorates or corrodes in a specific environment.

63
Q

Faraday’s Law of Electrolysis

A

Corrosion current can be converted to a corrosion rate using ______________.

64
Q

Surface Area Effect

A

The absolute equality between the anodic and cathodic currents expressed below does not mean that the current densities for these currents are equal.

65
Q

amplifying factor

stifling factor

A

If Sc/Sa is&raquo_space; 1, _____________

If Sc/Sa is &laquo_space;1, _____________

66
Q

Resistance control

A

This occurs when the electrolyte resistance is so high that the resultant current is not sufficient to appreciably polarize anodes or cathodes.

67
Q

corrosion current

A

The _____________ can be calculated from the corrosion potential and the thermodynamic potential.

68
Q

Stern-Geary approximation

A

This equation is known as:

69
Q

real polarization plots

A

The Tafel slopes in

70
Q

Theory of Cathodic Protection

A

Impressed current cathodic protection (ICCP) or by another metal that corrodes more readily than the metal being protected and therefore is sacrificed is the process.

71
Q

zero

A

If the metal is polarized slightly beyond the open -circuit potential, φA , of the anode, the corrosion rate remains ___________.

72
Q

degree of protection

A

Should the applied current fall below that required for complete protection, some ______________ occurs.

73
Q

This is associated with the activation energy required to initiate the electrochemical reaction at the electrode surface. It represents the energy barrier that must be overcome for the reaction to proceed.

A

Activation Polarization

74
Q

____________ activation overpotential can contribute to increased corrosion resistance by reducing the rate at which the metal reacts with the corrosive environment.

A

High

75
Q

Activation polarization is due to ______________ that are an inherent part of the kinetics of all electrochemical reactions.

A

retarding factors

76
Q

The __________________ is the single most important variable that explains the large differences in the rate of hydrogen production on metallic surfaces. It is influenced by factors such as the nature of the reactants, the specific electrochemical system, and the presence of catalysts.

A

exchange current density

77
Q

________________ is often added to power cells such as the popular alkaline primary cells to stifle the thermodynamically favored production of gaseous hydrogen and prevent unpleasant incidents.

A

Mercury

78
Q

______________ batteries (car batteries) can provide power in a highly acidic environment in a relatively safe manner unless excessive charging currents are used.

A

Lead acid

79
Q

This type of overpotential arises from the variation in ion concentrations at the electrode interface.

A

Concentration polarization

80
Q

When a chemical species participating in a corrosion process is in short supply, the mass transfer of that species to the corroding surface can become __________________.

A

rate controlling

81
Q

Mass transport to a surface is governed by three forces, that is, _____________, _____________, and _____________.

A

diffusion, migration, and convection

82
Q

In mass transport, the ______________ term is negligible since it only affects charged ionic species while the ______________ force disappears in stagnant conditions.

A

migration; convection

83
Q

The flux of a species O to a surface from the bulk is described with _______________.

A

Fick’s first law

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