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NACE 2008 Student Manual! START OF CHAPTER 1 Corrosion is an electrochemical process involving A) flow of protons and electrons B) flow of neutrons and ions C) flow of protons and ions D) flow of electrons and ions E) flow of resistance and resistivity - correct answer d Metal loss or corrosion occurs at the A) cathode B) anode C) electronic path D) metallic path - correct answer b What are the four parts of the corrosion cell A) anode, resistor, electrolyte, metallic path B) anode, cathode, electron, electronic path C) anode, cathode, electrolyte, metallic path - correct answer c True or False (t or f): Ions exist only in the electrolyte? - correct answer t Electrons flow in a corrosion cell by which of the following paths? A) anode to cathode via electrolyte B) cathode to anode via electronic path C) anode to cathode via electronic path - correct answer c At the cathodic surface in a corrosion cell, the electrons from the meet ions from the solution. A) cathode, hydrogen B) cathode, OH- C) anode, hydrogen D) anode, OH- - correct answer c
NACE CP2 – EXAM question and
answers latest 2023
Oxidation of the metal occurs at the surfaces and reduction of ions occurs at the. A) anodic, hydrogen, cathodes B) cathode, OH-, anodic C) anodic, OH-, cathodes D) cathode, anodic, electrolyte E) cathode, hydrogen, electrolyte - correct answer a True or false Is oxidation necessarily associated with oxygen? - correct answer f Current flow in a corrosion cell flows which path: A) anode to metallic path to cathode B) anode to electronic path to cathode C) cathode to metallic to anode D) cathode to electrolyte to anode E) anode to electrolyte to cathode Voltage is the measure of the electrochemical difference between two electrodes in an electrolyte - correct answer e is the measure of the electrochemical difference between two electrodes in an electrolyte A) current B) resistance C) error D) ohms E) ohms-cm F) voltage - correct answer f The represents the reversible work to move a unit charge from the electrode surface through the solution to the reference electrode A) current potential B) electrode potential C) resistance potential D) ohms potential E) Faraday potential - correct answer b Metals occur in nature in the form of various chemical compounds referred to as
E) platinum - correct answer a Electromotive force (emf), is in sign and magnitude to the electrode potential of the less the electrode potential of the. A) unequal, cathode, anode B) unequal, anode, cathode C) equal, cathode, anode D) equal, anode, cathode - correct answer d The driving force for electrochemical corrosion is A) current B) voltage C) resistance D) ohms E) siemens-cm - correct answer b In relation to a corrosion cell, is the net transfer of electric charge per unit time A) current B) voltage C) resistance D) ohms E) siemens-cm - correct answer a If a metallic path connects two electrodes inside an electrolyte, the difference will cause a to flow between them A) current, voltage B) resistance, current C) resistance, voltage D) voltage, current E) current, resistance - correct answer d The more useful method of organizing metals in order of their tendency to corrode is A) emf series B) pgp series C) nuclear series D) electron series E) galvanic series - correct answer e
products and reactants of the cell A) Ernest Equation B) Faraday Equation C) Ohm's Law Equation D) Nernst Equation E) Uniform Equation - correct answer d Given the Nernst Equation, using the Valence of Common Metals Table, and using the partial Standard emf Series of Metals solve: What is the potential of zinc in a 0.01 molar zinc chloride solution at 25C? A) - 0.892V B) - 0.287V C) - 0.827V D) - 0.297V E) - 0.889V - correct answer c E= - 0.763 + (0.059/2) * log (0.71 *0.01/1) = - 0.827V Standard conditions for pure metals in the emf series are based on one unit activity of metal ions in the electrolyte at C with no impurities in the metal or electrolyte and with reference to a standard electrode. A) 25, hydrogen B) 35, hydrogen C) 25, CSE D) 35, CSE E) 25, SSC F) 35, SSC - correct answer a The the concentration of metal ions in the electrolyte, the the metal. A) lower, less active B) higher, less active C) lower, more active D) higher, less active - correct answer b The expresses the exact electromotive force of a cell in terms of the activities of
What is the most common of the cathodic depolarizers, that can maintain and promote a cathodic reaction? A) CO B) oxygen C) carbon D) OH- E) Hydrogen - correct answer b Most corrosion on pipelines is on the portion of the pipe A) sides B) top C) bottom - correct answer c If a pipe is running through a section of pavement and through a section of non pavement: A) anode is the metal outside the pavement, the cathode is the metal under the pavement B) anode is the metal under the pavement, the cathode is the metal outside the pavement C) cathode is the metal under the pavement, the anode is the metal outside the pavement - correct answer b In a metal ion concentration cell, the surface in contact with concentration of metal ions acts as the A) lower, anode B) lower, cathode C) higher, anode D) higher cathode - correct answer a Theoretically, the potential of a structure changes by about mV for each pH unit A) 40 B) 50 C) 20 D) 70 E) 60 - correct answer e The corrosion potential of a metal might be - 500mV in an environment with a pH of 7, but the corrosion potential might be at a pH of 8? A) - 440mV B) - 660mV
C) - 300mV D) - 560mV - correct answer d True or false (t or f) an acidic pH can be harmful to concrete, such as reinforced concrete structures? - correct answer t A pH of less than is considered to be harmful to concrete? A) 4 B) 6 C) 5 D) 2 E) 8 - correct answer c The rate of corrosion is directly to flow? A) inproporinate, current B) inproporinate, voltage C) proportional, voltage D) proportional, current - correct answer d If a 1 Amp CP system must last 40 years and the electrochemical equivalent for silicon chromium cast iron anodes is 0.75 lb/A-yr, how many pounds of anodes are needed? A) 50lbs B) 35lbs C) 25 lbs D) 45lbs E) 30lbs - correct answer e All things being equal, the greater the magnitude of the difference between two voltages of metals, the the current flow and rate of corrosion A) higher B) lower - correct answer a True or False ( t or f) Magnesium will corrode at a slower rate when connected to steel rather than zinc? - correct answer f Which reference electrode is considered a primary reference electrode because it is used to determine the potential of other secondary reference electrodes that are better suited for field use?
Polarization the potential difference between the anode and the cathode and by Ohm's Law, the current and the corrosion rate until an equilibrium is reached When doing a structure to electrolyte potential , the structure is connected via the terminal and the reference is connected via the terminal A) negative , positive B) positive, negative - correct answer b A potential of - 0.810Vcse converted to Calomel (SCE) A) +0.306 sce B) - 0.750 sce C) - 0.735 sce - correct answer c A potential of - 0.810Vcse converted to Ag/AgCI (SSC) A) +0.306 ssc B) - 0.735 ssc C) - 0.750 ssc - correct answer c A potential of - 0.810Vcse converted to Zinc (ZRE) A) +0.306 zre B) - 0.735 zre C) - 0.750 zre - correct answer a True or False (t or f) The potential of a STATIONARY reference electrode should be checked from time to time with a portable reference electrode that is known to be accurate under "no current" conditions. - correct answer t As current is impressed on a metal over time, where does polarization occur? A) at the anode and the cathode B) at the anode C) at the cathode - correct answer a A) lowers, drops, decreases B) increases, increases, decreases C) lowers, increases, decreases D) lowers, drops, decreases - correct answer d
Depolarizers include: I dissolved oxygen II microbiological activity III water flow A) only I B) only II C) I and II D) I, II , III - correct answer d The name for the current that exists during the steady state of polarization is called the of the system A) telluric current B) dynamic current C) corrosion current D) mixed potential current E) closed current - correct answer c The potential normally measured between the polarized cathode potential and the polarized anode potential A) mixed potential B) corrosion potential C) corrosion current D) open circuit potential - correct answer a are the potentials of the cathode and anode when the corrosion current is zero A) mixed potentials B) corrosion potentials C) corrosion current potentials D) open circuit potentials - correct answer d is the result of the reaction steps at the structure/electrolyte interface including the actual transfer of charge A) activation polarization B) concentration polarization C) mixed polarization D) reactant polarization - correct answer a In concentrated acids, polarization predominates A) activation polarization
An increase in ions will result in a in resistivity A) increase B) decrease - correct answer b The effect of current concentrated on a small area will be than the effect of the same amount of current on a area. A coated structure will polarize more rapidly than a bare structure A) larger, larger B) less, larger C) greater, smaller D) smaller, smaller E) greater, larger - correct answer e True or False (t or f) A small anode and a large cathode is desirable - correct answer f A(n) in temperature has a tendency to chemical reactions, which the electrodes and current A) increase, increase, depolarizes, increases B) increase, increase, depolarizes, decrease C) decrease, decrease, polarize, increase D) decrease, increase, polarize, decrease - correct answer a A(n) in temperature results in a(n) in polarization A) increase, decrease B) increase, increase C) decrease, increase D) decrease, decrease - correct answer c movement results in a in polarization and a(n) in current A) decreased, decrease, decrease B) decreased, increase, decrease C) increased, increase, decrease D) increased, decrease, decrease E) increased, increase, increase - correct answer d A(n) in the metal ion concentration of the anode metal results in a(n) in polarization of the anode and a(n) in current
A) increase, decrease, decrease B) decrease, decrease, decrease C) decrease, increase, decrease D) increase, increase, decrease E) decrease, decrease, increase - correct answer e Polarization of the cathode can be affected by the concentration of cathodic A) CO2, OH- B) oxygen, OH- C) carbon, OH- D) oxygen, hydrogen - correct answer d In regards to cathodic reactants, a(n) in the concentration of either of the reactants of oxygen or hydrogen will polarization of the cathode and current and vice versa A) increase, decrease, decrease B) decrease, decrease, decrease C) increase, decrease, increase D) increase, increase, decrease E) decrease, decrease, increase - correct answer c Passivity can be defined as the A) gain of chemical reactivity B) polarization of chemical reactivity C) loss of chemical reactivity D) depolarization of molecular reactivity E) polarization of molecular reactivity - correct answer c The region is when a slight increase in corrosion potential causes the corrosion current to increase A) transpassive B) passive C) nonpassive D) active - correct answer d The region is when the corrosion potential increases to a certain point, however, the corrosion current suddenly decreases and remain essentially constant A) transpassive B) passive reactants, such as or ions
C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack - correct answer f This corrosion occurs when two dissimilar metals are connected. The potential of the two metals creates a voltage difference, the driving force for corrosion. A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack - correct answer a Localized corrosion that occurs over a small area of the metal surface and leaves holes in the surface. A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack - correct answer e This is a local corrosion attack at the grain boundaries of an alloy. It is caused by a difference in element composition near the boundaries, compared to the rest of the alloy. A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack - correct answer b This type of corrosion involves the certain removal of one of the elements from an alloy. A) Galvanic attack B) intergranular attack
C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack - correct answer c This corrosion is associated with rapid movement of a corrosive fluid over a metal, removing corrosion products. A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack - correct answer d results from the reaction of the metal with a corrosive environment and the presence of a stress A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) environmental cracking F) crevice corrosion G) uniform attack - correct answer d In general, hydrogen is generated in neutral environments at - mV CSE A) 1, B) 1, C) 1, D) 1,200 - correct answer b For aluminum, the polarized potential must be kept below - mV CSE to avoid alkali corrosion A) 1, B) 1, C) 1, D) 1,200 - correct answer d For titanium, the maximum
START OF CHAPTER2:
Corrosion of the metal will cease once the applied cathodic protection current the corrosion current. A) equals B) equals or exceeds C) falls below - correct answer b As the potentials of the sites polarize toward the potentials of the sites, corrosion current is. A) anodic, cathodic, increase B) cathodic, anodic, reduced C) cathodic, anodic, increase D) anodic, cathodic, decrease - correct answer b Polarization occurs in a step-like manner with the more or sites polarizing first. A) positive, anodic B) positive, cathodic C) negative, anodic D) negative, cathodic - correct answer b To mitigate corrosion, all existing cathode sites must be electronegatively polarized to a potential to the open circuit potential of the most potential existing on the structure. A) equal, inactive, cathode B) unequal, active, anode C) unequal, inactive, cathode D) equal, active, anode - correct answer d Polarization of the to the potential of the anodes is the true criterion for eliminating corrosion. A) cathodes, closed circuit B) anodes, closed circuit C) cathodes, open circuit D) anodes, open circuit - correct answer c Bare Pipe: What is the current required to protect an uncoated 30.48 cm (12 in.) diameter steel pipeline 1,524 m (5,000 ft) in length that is buried in soil with a resistivity
of 10,000 Ω-cm? Assume experience has shown that adequate levels of cathodic protection can be achieved from 10.76 mA/m 2 (1 mA/ ft 2 ) of bare surface area. A) 16.8A B) 15.7A C) 14.7A D 13.8A - correct answer b Coated Pipe: What is the current required to protect an uncoated 30.48 cm (12 in.) diameter steel pipeline 1,524 m (5,000 ft) in length that is buried in soil with a resistivity of 10,000 Ω-cm? Assume that 5 percent of the pipe contains holidays or defects in the coating A)0.8538A B) 1.785A C) 0.785A D) 2.754A - correct answer c For a cathodic protection system, a(n) in the cathodic polarization is desired to the current requirement for the structure. A) decrease, increase B) increase, increase C) decrease, decrease D) increase, decrease - correct answer d The current required for cathodic protection generally is in low pH (acids) than in high pH (basic) and neutral environments. A) lower B) greater - correct answer b What two phenomena account for the increase in CP current requirement in low pH environments? A) shift in the negative directions of the structure's open circuit cathode potential / a flattening of cathodic polarization curve for the structure B) shift in the positive direction of the structure's open circuit cathode potential / a flattening of cathodic polarization curve for the structure - correct answer b
