Chapter 17

Question 1

dissolution

Answer 1

material loss due to corrosion and scaling of the material

Question 2

oxidation

Answer 2

formation of oxides on the material that normally results in weight gain

Question 3

corrosion/oxidation is driven by _________

Answer 3

transfer of electrons

Question 4

metals readily ______ electrons

Answer 4

give up

Question 5

oxidation reaction

Answer 5

M -> M^+n+ +ne

Question 6

reduction reactoin

Answer 6

M^n+ + ne -> M

Question 7

what reaction happens at an anode

Answer 7

oxidation

Question 8

what reaction happens at a cathode

Answer 8

reduction

Question 9

what is the standard condition to test potential

Answer 9

platinum electrode with 1M H+ ions electrolyte

Question 10

noble metals

Answer 10

inert metals

Question 11

active metals

Answer 11

highly reactive

Question 12

the metal _______ on the galvanic series table corrodes (gets oxidized)

Answer 12

lower

Question 13

net voltage of circuit

Answer 13

V = V2 - V1
V2 = reduction
V1 = oxidation

Question 14

when does a redox reaction take place as expected

Answer 14

when change in V is positive

Question 15

what happens if molarities of electrolytes are not 1M

Answer 15

must adjust using equation

Question 16

passivity

Answer 16

some metals react with oxygen in the air and form a very stable oxide on a metal’s surface which protects it from corrosion

Question 17

sacrificial anodes

Answer 17

attach a sacrificial anode to a metal that is more likely to corrode to stop corrosion of important material (cathode)

Question 18

sacrificial anode materials

Answer 18

zinc, magnesium, aluminum

Question 19

impressed current cathodic protection

Answer 19

pipeline connected to an external electric circuit that drives electrons in the opposite way they would normally flow

Question 20

galvanizing

Answer 20

applying a protective coating of zinc onto steel since zinc is more reactive

Question 21

uniform surface corrosion

Answer 21

-protected against by generic corrosion prevention
-occurs all over the material

Question 22

galvanic corrosion

Answer 22

two metals with different EMF are put together in an electrolyte, less noble metal corrodes while more noble metal is protected

Question 23

galvanic corrosion, rate of corrosion is proportional to ______

Answer 23

surface area in contact

Question 24

crevice corrosion

Answer 24

when there is a concentration gradient in the electrolyte, typically occurs in tight corners where proper mixing is difficult

Question 25

intergranular corrosion

Answer 25

forms on microstructure level - related to formation of phases on grain boundaries

Question 26

selective leaching

Answer 26

intentional dissolution of an element from a material that leaves behind a porous material with poor mechanical performance

Question 27

erosion - corrosion

Answer 27

especially prevalent in pipes where a fluid is causing corrosion and the movement of the fluid causes erosion

Question 28

stress corrosion

Answer 28

combination of loading and corrosive environment, stress from the load lowers activation energy required for corrosion