30 Questions
What is an important factor to consider when selecting a corrosion inhibitor?
The compatibility of the inhibitor with the metal, corrosive environment, and desired application conditions
What is a mechanism by which corrosion inhibitors protect metal surfaces?
Adsorption on the metal surface, creating a barrier to corrosive species
Which thermodynamic parameter indicates a spontaneous corrosion reaction?
ΔG° < 0
What does a negative value of ΔG° for a corrosion reaction imply?
Thermodynamic favorability for corrosion
What is a desirable characteristic for an ideal corrosion inhibitor?
Low cost and easy availability, making it a practical solution
In a galvanic corrosion cell, which metal is the anode?
The metal with the more negative electrode potential
What is a potential disadvantage of using corrosion inhibitors?
They can interfere with other surface treatment processes
What is the most important factor to consider when selecting a corrosion inhibitor for a specific application?
The effectiveness of the inhibitor, as it affects the metal's protection
What is the Pourbaix diagram used for?
Predicting the thermodynamics of corrosion reactions
In a Pourbaix diagram, what does the immunity region correspond to?
Thermodynamic stability of the metal
What is a mechanism by which corrosion inhibitors can form a protective layer on the metal?
Anodic passivation, forming a protective oxide layer on the metal
What is a characteristic that can influence the effectiveness of a corrosion inhibitor?
The inhibitor's high reactivity with the metal surface, potentially leading to unintended side effects
What is the correct statement about corrosion potential and corrosion current?
They are two terms for the same phenomenon.
What does an Evans diagram depict in the context of corrosion?
The corrosion potential and corrosion current density for a metal in a specific environment.
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?
Type I
How many methods of determining corrosion rate are there?
3
What is the basic principle of the weight loss method for determining corrosion rate?
Measuring the change in the weight of a metallic sample
What does the variable 'A' represent in the corrosion rate formula K.W/A.T.D?
Sample area
What is the unit of measurement used to express corrosion rate?
mils per year (mpy)
How is corrosion rate evaluated for metallic materials in non-oxidizing media?
By measuring the weight loss of the sample
What is the primary purpose of comparing results with and without the addition of an inhibitor in the corrosion rate experiment?
To determine the efficiency of the inhibitor
What is the primary purpose of the Thermometric Method (Mylius method)?
To compare the corrosion rate and inhibition efficiency of various inhibitors
What is the initial step in the Mylius method?
Dropping a test piece of the metal into a definite volume of corrosive media
What does the reaction number (R.N.) represent in the Mylius method?
The amount of heat generated during the reaction
In a Pourbaix diagram, which zone is characterized by a high rate of oxidation reactions?
Oxidation zone
What is represented on the vertical axis of a Pourbaix diagram?
Electrode potential (Eh)
What do current-potential curves primarily display in electrochemical studies?
The relationship between the applied potential and resulting current
Which of the following statements about corrosion current and corrosion potential is true?
Corrosion current is the rate at which corrosion occurs, while corrosion potential is the tendency for a metal to corrode
In which zone of a Pourbaix diagram is a metal immune to corrosion?
Immunity zone
What can be inferred about a metal's corrosion susceptibility from its current-potential curve?
Its electrochemical behavior and corrosion susceptibility
Test your knowledge of corrosion diagrams, including Evans diagrams, and their relation to electrochemistry concepts like corrosion potential and corrosion current.
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