Corrosion Diagrams and Electrochemistry Quiz
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Questions and Answers

What is an important factor to consider when selecting a corrosion inhibitor?

  • The brand name of the inhibitor
  • The ease of application of the inhibitor
  • The compatibility of the inhibitor with the metal, corrosive environment, and desired application conditions (correct)
  • The color of the inhibitor

    • What is a mechanism by which corrosion inhibitors protect metal surfaces?

  • Adsorption on the metal surface, creating a barrier to corrosive species (correct)
  • Cathodic poisoning, reducing the activity of cathodic sites on the metal surface
  • Film formation by reaction with the metal, increasing its reactivity
  • Anodic passivation, forming a protective oxide layer on the metal

    • Which thermodynamic parameter indicates a spontaneous corrosion reaction?

  • ΔG° > 0
  • ΔG° < 0 (correct)
  • ΔH° < 0
  • ΔS° > 0

    • What does a negative value of ΔG° for a corrosion reaction imply?

    <p>Thermodynamic favorability for corrosion</p> Signup and view all the answers

    What is a desirable characteristic for an ideal corrosion inhibitor?

    <p>Low cost and easy availability, making it a practical solution</p> Signup and view all the answers

    In a galvanic corrosion cell, which metal is the anode?

    <p>The metal with the more negative electrode potential</p> Signup and view all the answers

    What is a potential disadvantage of using corrosion inhibitors?

    <p>They can interfere with other surface treatment processes</p> Signup and view all the answers

    What is the most important factor to consider when selecting a corrosion inhibitor for a specific application?

    <p>The effectiveness of the inhibitor, as it affects the metal's protection</p> Signup and view all the answers

    What is the Pourbaix diagram used for?

    <p>Predicting the thermodynamics of corrosion reactions</p> Signup and view all the answers

    In a Pourbaix diagram, what does the immunity region correspond to?

    <p>Thermodynamic stability of the metal</p> Signup and view all the answers

    What is a mechanism by which corrosion inhibitors can form a protective layer on the metal?

    <p>Anodic passivation, forming a protective oxide layer on the metal</p> Signup and view all the answers

    What is a characteristic that can influence the effectiveness of a corrosion inhibitor?

    <p>The inhibitor's high reactivity with the metal surface, potentially leading to unintended side effects</p> Signup and view all the answers

    What is the correct statement about corrosion potential and corrosion current?

    <p>They are two terms for the same phenomenon.</p> Signup and view all the answers

    What does an Evans diagram depict in the context of corrosion?

    <p>The corrosion potential and corrosion current density for a metal in a specific environment.</p> Signup and view all the answers

    What type of Evans diagram represents a situation where the cathodic reaction rate is controlled by the rate of mass transport of the reacting species to the electrode surface?

    <p>Type I</p> Signup and view all the answers

    How many methods of determining corrosion rate are there?

    <p>3</p> Signup and view all the answers

    What is the basic principle of the weight loss method for determining corrosion rate?

    <p>Measuring the change in the weight of a metallic sample</p> Signup and view all the answers

    What does the variable 'A' represent in the corrosion rate formula K.W/A.T.D?

    <p>Sample area</p> Signup and view all the answers

    What is the unit of measurement used to express corrosion rate?

    <p>mils per year (mpy)</p> Signup and view all the answers

    How is corrosion rate evaluated for metallic materials in non-oxidizing media?

    <p>By measuring the weight loss of the sample</p> Signup and view all the answers

    What is the primary purpose of comparing results with and without the addition of an inhibitor in the corrosion rate experiment?

    <p>To determine the efficiency of the inhibitor</p> Signup and view all the answers

    What is the primary purpose of the Thermometric Method (Mylius method)?

    <p>To compare the corrosion rate and inhibition efficiency of various inhibitors</p> Signup and view all the answers

    What is the initial step in the Mylius method?

    <p>Dropping a test piece of the metal into a definite volume of corrosive media</p> Signup and view all the answers

    What does the reaction number (R.N.) represent in the Mylius method?

    <p>The amount of heat generated during the reaction</p> Signup and view all the answers

    In a Pourbaix diagram, which zone is characterized by a high rate of oxidation reactions?

    <p>Oxidation zone</p> Signup and view all the answers

    What is represented on the vertical axis of a Pourbaix diagram?

    <p>Electrode potential (Eh)</p> Signup and view all the answers

    What do current-potential curves primarily display in electrochemical studies?

    <p>The relationship between the applied potential and resulting current</p> Signup and view all the answers

    Which of the following statements about corrosion current and corrosion potential is true?

    <p>Corrosion current is the rate at which corrosion occurs, while corrosion potential is the tendency for a metal to corrode</p> Signup and view all the answers

    In which zone of a Pourbaix diagram is a metal immune to corrosion?

    <p>Immunity zone</p> Signup and view all the answers

    What can be inferred about a metal's corrosion susceptibility from its current-potential curve?

    <p>Its electrochemical behavior and corrosion susceptibility</p> Signup and view all the answers

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