Corrosion 8

Question 1

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

Answer 1

Salt concentration cell

Question 1

Occurs due to differences in potential between differently Aerated areas.

Answer 1

Differential aeration cell

Question 2

• A list that describes the arrangement of elements in the order of their increasing electrode potential values.

Answer 2

Electrochemical Series

Question 3

is an orderly arrangement of the standard potentials for all metals.

Answer 3

Emf Series

Question 4

• Determines the electrochemical potential and nobility of metals.

Answer 4

Galvanic Cell

Question 5

Pure mercury is placed at the bottom of the tube, which is covered with a paste of mercury- mercurous

Answer 5

Calomel Reference Electrode

Question 6

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.

Answer 6

Silver-Silver Chloride Reference Electrode

Question 7

• Consists of metallic copper immersed in saturated copper sulfate.
• The electrode’s precision, though slightly lower than that of calomel or silver chloride electrodes, is still sufficient for most corrosion studies.

Answer 7

Saturated Copper-Copper Sulfate Reference Electrode

Question 8

of electrolysis 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.

Answer 8

Faraday’s empirical laws

Question 9

• current produced in an electrochemical cell during corrosion.

Answer 9

CORROSION CURRENT

Question 10

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

Answer 10

CORROSION RATE

Question 11

provides a way to calculate corrosion rate.

Answer 11

Corrosion current

Question 12

A reduction current that occurs when electrons flow from the electrode surface to a species in solution. For example, oxygen reduction in a fuel cell.

Answer 12

Cathodic current

Question 13

An oxidation current that occurs when electrons flow into the electrode from a species in solution. For example, hydrogen oxidation in a fuel cell.

Answer 13

Anodic current

Question 14

Have widespread applications in resisting corrosion but it should be remembered that they do not resist all corrosives.

Answer 14

STAINLESS STEEL

Question 15

are also more susceptible to localized corrosion than ordinary structural steels.
- less resistant than ordinary structural steel.
- Frequently, the quality of stainless steel is checked with a magnet.

Answer 15

Stainless alloys

Question 16

The corrosion resistance of a pure metal is usually better than that of one containing impurities or small amounts of other elements. However, pure metals are usually expensive and relatively soft and weak.

Answer 16

METAL PURIFICATION

Question 17

is achieved by supplying electrons to the metal structure to be protected.

Answer 17

Cathodic protection

Question 18

This type of CP uses a more reactive metal (the sacrificial anode) that corrodes preferentially to the metal structure (the cathode) that needs to be protected.

Answer 18

GALVANIC OR SACRIFICIAL ANODE METHOD

Question 19

used for cathodic protection consist of magnesium-base and aluminum-base alloys and, to a lesser extent, zinc.

Answer 19

Sacrificial metals

Question 20

serve essentially as sources of portable electrical energy. They are useful particularly when electric power is not

Answer 20

Sacrificial anodes

Question 21

This type of CP uses an external power source (impressed current) to provide the electrons required to cathodically protect the structure.
- An external de power supply is connected to an underground tank. The negative terminal of the power supply is connected to the tank, and the positive to an inert anode such as graphite or Duriron.

Answer 21

IMPRESSED CURRENT METHOD

Question 22

formation of a protective film on metals by externally applied anodic currents.
- exhibiting an active-passive behavior in order to form a passive film.
- maintaining passive a metal with an active–passive behavior when placed in an aggressive environment.

Answer 22

ANODIC PROTECTION

Question 23

an electronic device that maintains a metal at a constant potential with respect to a reference electrode to anodically protect a structure.

Answer 23

POTENTIOSTAT