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NACE CP2 – EXAM with correct answers
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 - ANSWER: ➡ d Metal loss or corrosion occurs at the A) cathode B) anode C) electronic path D) metallic path - 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 - ANSWER: ➡ c True or False (t or f): Ions exist only in the electrolyte? - 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 - 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- - ANSWER: ➡ c 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 - ANSWER: ➡ a True or false Is oxidation necessarily associated with oxygen? - ANSWER: ➡ f Current flow in a corrosion cell flows which path:
Metals occur in nature in the form of various chemical compounds referred to as
A) ores B) anodic metals C) cathodic metals D) carbohydrates - ANSWER: ➡ a The amount of energy required by a metal during the refining process determines the ___ or _______ of the metal. A) current, active state B) voltage, active state C) active resistance, voltage D) resistance, active state E) current, active resistance - ANSWER: ➡ b During the refining stage of metal the ____ the energy, the more ____ the metal and the more tendency it has to corrode. A) higher, inactive B) lower, active C) higher, active D) lower, inactive - ANSWER: ➡ c What is the most common iron ore? A) hemophite B) hematite C) magnesium
D) calcium E) aluminum - ANSWER: ➡ b True or false Iron is considered thermodynamically unstable? - ANSWER: ➡ t True or false Gold is more noble than zinc? - ANSWER: ➡ t Which of the following metals is most active? A) magnesium B) copper C) iron D) nickel E) platinum - 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 - ANSWER: ➡ d The driving force for electrochemical corrosion is ____ A) current
E) galvanic series - ANSWER: ➡ e The ____ expresses the exact electromotive force of a cell in terms of the activities of products and reactants of the cell A) Ernest Equation B) Faraday Equation C) Ohm's Law Equation D) Nernst Equation E) Uniform Equation - 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 - 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 - 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 - ANSWER: ➡ b In reference to the temperature in a corrosion cell, in most cases, electrode at the _____ temperature becomes the ____ A) lower, anode B) higher, cathode C) lower, cathode D) higher, anode - ANSWER: ➡ d During metal fabrication of structures, highly stressed areas of a metal will tend to be at ____ energy levels, thus more ____ than less stressed areas A) higher, active
D) oxygen, metal ion - ANSWER: ➡ d 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 - ANSWER: ➡ b Most corrosion on pipelines is on the ____ portion of the pipe A) sides B) top C) bottom - 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 - 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 - 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 - 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 - ANSWER: ➡ d True or false (t or f) an acidic pH can be harmful to concrete, such as reinforced concrete structures? - ANSWER: ➡ t A pH of less than ____ is considered to be harmful to concrete? A) 4 B) 6 C) 5 D) 2
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? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE - ANSWER: ➡ e Most common used reference electrode for measuring potentials of underground structures? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE - ANSWER: ➡ a True or false (t or f) The potential of a reference electrode in the sun can decrease from 10 to 50mV versus an electrode kept in the dark? - ANSWER: ➡ t Which reference electrode is mostly commonly used in seawater? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE - ANSWER: ➡ b
Which reference electrode is mostly commonly used in concrete structures? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE - ANSWER: ➡ b Which of the following is primarily a laboratory electrode? A) CSE B) Ag/AgCI C) Calomel D) Zinc - ANSWER: ➡ c 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 - ANSWER: ➡ b A potential of -0.810Vcse converted to Calomel (SCE) A) +0.306 sce B) -0.750 sce C) -0.735 sce - ANSWER: ➡ c A potential of -0.810Vcse converted to Ag/AgCI (SSC)
C) lowers, increases, decreases D) lowers, drops, decreases - 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 - 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 - 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 - 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 - 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 - ANSWER: ➡ a In concentrated acids, _______ polarization predominates A) activation polarization B) concentration polarization C) mixed polarization D) reactant polarization - ANSWER: ➡ a _______ is the result of reaction steps involving the diffusion of reactants up to the reaction products away from the reaction surface A) activation polarization B) concentration polarization C) mixed polarization D) reactant polarization - ANSWER: ➡ b
A) increases, decreases B) decreases, decreases C) increases, increases D) decreases, increases - ANSWER: ➡ c An increase in ions will result in a ____ in resistivity A) increase B) decrease - 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 - ANSWER: ➡ e True or False (t or f) A small anode and a large cathode is desirable - 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 - ANSWER: ➡ a A(n) ____ in temperature results in a(n) ____ in polarization A) increase, decrease B) increase, increase C) decrease, increase D) decrease, decrease - 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 - 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 - ANSWER: ➡ e Polarization of the cathode can be affected by the concentration of cathodic reactants, such as _____ or _____ ions A) CO2, OH-
