Types and Theories of Metal Corrosion

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What causes the formation of reddish brown scale on iron?

Formation of Fe2O3

Explain the formation of green scale on a copper vessel.

CuCO3 & Cu(OH)2

What are the two types of corrosion based on the way it occurs?

Dry corrosion and wet corrosion

Explain dry corrosion.

Direct chemical attack by dry gases like SO2, CO2, Cl2, H2S Signup and view all the answers

Describe wet corrosion and how it occurs.

Electrochemical attack on the metal with moisture and oxygen present in the atmosphere Signup and view all the answers

What is the fundamental principle of the electrochemical theory of corrosion?

Formation of anodic and cathodic regions on the same metal surface Signup and view all the answers

Explain the factors that affect the rate of galvanic corrosion.

Potential difference between anodic and cathodic regions, ratio of anodic area to cathodic area, environmental factors, tendency of the metal to exhibit passivity Signup and view all the answers

In a galvanic cell with iron and copper in contact, which metal acts as the anode and which as the cathode?

Iron acts as the anode and copper acts as the cathode. Signup and view all the answers

Describe what happens in a bimetallic couple in terms of corrosion.

The metal that is anodic corrodes while the metal that becomes cathodic is protected. Signup and view all the answers

Explain the reactions that take place in a galvanic cell with iron and copper electrodes.

At the anode: Fe → Fe2+ + 2e-, At the cathode: O2 + 2H2O + 4e- → 4 OH- Signup and view all the answers

What is differential aeration corrosion and how does it occur?

Differential aeration corrosion occurs when a metal surface is exposed to varying oxygen concentrations. Signup and view all the answers

Explain the process of rust formation on iron in the presence of copper in a galvanic cell.

2Fe2+ + 4OH- + O2 + 2H2O → 2 Fe(OH)2 → 2 [Fe2O3.3H2O] (Rust) Signup and view all the answers

What is the principle behind conductometry?

Conductometry is based on the measurement of electrical conductivity of a solution. Signup and view all the answers

How is iron estimated using potentiometry?

Potentiometry is a method based on the measurement of the potential of an electrochemical cell involving iron ions. Signup and view all the answers

Define IR spectroscopy and its application in self-study components.

IR spectroscopy is a technique that measures the vibrations of chemical bonds and is used for structural analysis in self-study components. Signup and view all the answers

Explain UV-Visible spectroscopy and its significance in self-study components.

UV-Visible spectroscopy measures the absorption of ultraviolet and visible light by a substance, providing information about its electronic structure. Signup and view all the answers

What is the electrochemical theory of corrosion based on?

The electrochemical theory of corrosion is based on the transformation of pure metal into undesired metallic compounds through chemical or electrochemical attack. Signup and view all the answers

How is the destruction or deterioration of metal by chemical or electrochemical attack defined?

The destruction or deterioration of metal by surrounding environment through chemical or electrochemical attack is known as corrosion. Signup and view all the answers