Understanding Metal Corrosion: Types, Causes, and Control
Corrosion is the destructive attack of a material by chemical or electrochemical reaction with its environment. When etching is accompanied by physical damage, then there is corrosion-erosion, or corrosive wear by friction.
- It is a natural process; there is a transformation of the material to a more stable compound, which is an oxide.
- Plastic or wood do not corrode; they can crack or break down.
- Corrosion of iron leads to oxidation.
Two Kinds of Corrosion
- Dry: When an attack occurs via a chemical reaction,
Acid-Base Reactions and pH Calculations: Solved Problems
1. Identifying Conjugate Acid-Base Pairs
Identify the conjugate acid-base pairs in the following reaction:
CH3COO– + HCN ⇄ CH3COOH + CN–
Solution:
According to the Bronsted-Lowry theory, an acid is a chemical species that can donate an H+ ion. A base is a species that can accept an H+ ion. Therefore, by reacting an acid with a base, a new acid and a new base will always be formed.
Looking at the acid-base reaction of this problem:
CH3COO– + HCN ⇄ CH3COOH + CN–
You can see that the species CH3COO– (
Read MoreMetallic Bonds: Properties, Theories, and Characteristics
Properties of Metals
Metals, identified by their group number in the periodic table, share a set of similar properties:
- Electrical and thermal conductivity
- Metallic luster
- Malleability
- Ductility
Metals are electropositive, forming cations. They have few electrons in their valence shell. Their valence load results in positive oxidation numbers, and they are easily oxidized. All metals are solid at ambient temperature and pressure, except for mercury, which is liquid. These properties are due to their structure
Read MoreAtomic Models and Periodic Table of Elements
Atomic Models Through History
Dalton’s Atomic Model (1808)
Dalton proposed that matter is formed of small particles called atoms, which are indivisible and indestructible. He stated that all atoms of the same element are identical and that atoms of different elements are distinguished by their mass and properties. Therefore, all atoms of the same element have the same properties.
Thomson’s Plum Pudding Model (1904)
Thomson suggested that the atom was a positively charged solid sphere in which electrons
Read MoreSteel Production and Ferrous Metals: Processes and Types
Blast Furnace Operation
- The raw material, consisting of iron ore (60%), coking coal (30%), and flux (10%), is introduced into the blast furnace.
- The furnace operates continuously.
- As the load descends from the top, its temperature increases until it reaches the bosh. Here, the temperature reaches 1650°C, and liquid iron is deposited in the crucible.
- The flux reacts with the ore to form slag, which floats on the molten iron. Slag is removed through a hole called the slag runner. This slag is used to
Iron and Calcium: Properties, Reactions, and Effects
The Iron Cation
Pure iron is a silvery-white, tenacious, and ductile metal. Commercial iron is rarely pure and often contains small amounts of carbides, silicides, phosphides, and sulfides of iron, and a bit of graphite. Iron dissolves in diluted hydrochloric acid and concentrated sulfuric acid, diluted with hydrogen evolution, and the formation of ferrous salt. With hot, concentrated sulfuric acid, it produces sulfur dioxide and ferric sulfate. Under experimental conditions with concentrated nitric
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