Corrosion

Question 1

determines whether the reaction is
spontaneous, non-spontaneous or at equilibrium .

Answer 1

Gibbs free energy

Question 1

quantifies the tendency of any
metal’
s to react with its environment.

Answer 1

CHANGE OF GIBBS FREE
ENERGY

Question 2

a simple
“chemical” reaction that can be used to understand how
electrochemical concepts can be applied to predict
corrosion tendency of a metal.

Answer 2

Corrosion of iron in an acid

Question 3

metal atoms lose
electrons and form metal ions

Answer 3

Oxidation

Question 4

non-metallic
substances such as oxygen gain
electron

Answer 4

Reduction

Question 5

overall corrosion reaction can be described in terms of

Answer 5

half-reactions

Question 6

corrosion of metals occurs
within a localized electrochemical
cell

Answer 6

corrosion cell.

Question 7

involves the spatial
separation of anodic and cathodic
areas on the metal surface leading
to formation of corrosion sites.

Answer 7

corrosion cell

Question 8

where oxidation occurs,
leading to the release of metal ions.

Answer 8

anode

Question 9

Reduction reactions take place at
the

Answer 9

cathode

Question 10

serves as a medium
for ion transport

Answer 10

electrolyte

Question 11

the potential difference
measured under standard conditions (1 M concentration, 1 atm
pressure, and a temperature of 25°C) for a half-cell reaction
relative to the SHE.

Answer 11

standard electrode potential

Question 12

quantifies the tendency of a metal to undergo
oxidation or reduction relative to a standard reference electrode

Answer 12

standard electrode potential

Question 13

historically important electrode. It is the halfcell in which hydrogen gas is bubbled over a
platinum electrode immersed in a solution having
a known concentration of hydrogen ions

Answer 13

STANDARD HYDROGEN ELECTRODE

Question 14

On coupling
one of them turns into anodic and the other cathodic such that
the cell potential becomes positive.

Answer 14

ELECTRO MOTIVE
FORCE (EMF) SERIES

Question 15

Hydrogen equilibrium bears

Answer 15

zero value

Question 16

most negative or
active half-cell tends to be

Answer 16

oxidized

Question 17

most
positive or noble half-cell tends to be

Answer 17

reduced

Question 18

Relations between the energy and the potential of a cell

Answer 18

NERNST EQUATION

Question 19

outline regions of
active corrosion, oxides/hydroxides
formation, and thermodynamic immunity
for a metal

Answer 19

Potential-pH diagrams/Pourbaix diagrams

Question 20

If the oxides/hydroxides protect the underlying metal, then
this region

Answer 20

passive region

Question 21

Thermodynamically immune region ensures complete
prevention of metal from corrosio

Answer 21

anodic protection and cathodic protection

Question 22

control the cathodic and
anodic currents that are integral components of
corrosion processes

Answer 22

polarization effects

Question 23

deviation in
the potential (voltage) of an electrode from its
equilibrium

Answer 23

Overpotential

Question 24

quired to
initiate the electrochemical reaction at the electrode
surface.

Answer 24

activation energy

Question 25

Activation polarization is due to

Answer 25

retarding factors

Question 26

most important
variable that explains the large differences in the rate of
hydrogen production on metallic surfaces.

Answer 26

exchange current density

Question 27

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

Answer 27

Mercury

Question 28

provide power in a highly
acidic environment in a relatively safe
manner unless excessive charging
currents are used.

Answer 28

lead acid battery

Question 29

arises from the variation in ion
concentrations at the electrode interface

Answer 29

CONCENTRATION POLARIZATION

Question 30

related to the mass transport limitations of reactants or
products to or from the electrode surface.

Answer 30

CONCENTRATION POLARIZATION

Question 31

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

Answer 31

become rate limiting

Question 32

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

Answer 32

diffusion, migration, and
convection.

Question 33

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

Answer 33

Fick’s first law.