10 Questions
What is the primary reason why noble metals are resistant to corrosion?
They have a low reactivity
What is the result of the oxidation reaction during the electrochemical process of corrosion?
The metal releases electrons
Which of the following factors does not affect the rate of corrosion?
Magnetic properties of metal
What is the product of the rusting of Iron?
Fe2O3.xH2O
What is the role of the anode in the electrochemical process of corrosion?
It is the area where oxidation occurs
Why does corrosion occur more readily at cuts and bends in a metal?
Because the metal is more strained at these areas
What is the effect of a higher temperature on the rate of corrosion?
It increases the rate of corrosion
What is the role of moisture in the corrosion process?
It enhances corrosion by providing a medium for the electrochemical reaction
Which of the following is an example of an electrolyte that can enhance corrosion?
Saline water
What is the pH range in which corrosion is more likely to occur?
pH < 7
Study Notes
What is Corrosion?
- Corrosion is a natural, irreversible process where pure metal (except noble metals) is converted into chemically stable compounds like oxides, sulfides, hydroxides, and carbonates.
- It's a slow deterioration of metal due to atmospheric gases, resulting in the formation of more stable compounds.
Common Example of Corrosion
- Rusting of Iron (Fe2O3.xH2O) is the most common corrosion.
Factors Affecting Corrosion
- Reactivity of metal: More reactive metals corrode more readily.
- Strain in metal: Corrosion occurs readily at cuts and bends in metal.
- Presence of impurities: Impurities in pure metal increase the likelihood of corrosion.
- Presence of electrolyte: Saline water (electrolyte) accelerates corrosion.
- Air and moisture: Rusting of Iron is a classic example.
- pH: Acidic mediums (pH < 7) are more corrosive than basic or neutral mediums.
- Temperature: Higher temperatures increase the rate of corrosion.
Electrochemical Theory of Corrosion (Wet Theory of Corrosion)
- Metals exposed to air, moisture, soil, etc. undergo corrosion through an electrochemical process.
- Separate anode and cathode areas form on the metal surface.
- Corrosion occurs at anodic areas through oxidation reactions, releasing electrons.
Learn about corrosion, a natural process that converts pure metals into stable compounds, and its effects on metal surfaces. Understand the deterioration of metals due to atmospheric gases, resulting in the formation of compounds like oxides and sulphide.
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