what is rusting of iron? what conditions are required for rusting to take place how can we prevent rusting?
Answers
Explanation:
#rusting
Rusting of iron refers to the formation of rust, a mixture of iron oxides, on the surface of iron objects or structures. This rust is formed from a redox reaction between oxygen and iron in an environment containing water (such as air containing high levels of moisture). The rusting of iron is characterized by the formation of a layer of a red, flaky substance that easily crumbles into a powder.
Rusting of Iron
This phenomenon is a great example of the corrosion of metals, where the surfaces of metals are degraded into more chemically stable oxides. However, the term ‘rusting’ is generally used to refer to the corrosion of objects made of iron or iron-alloys.
#Why is Rusting an Undesirable Phenomenon?
Rusting causes iron to become flaky and weak, degrading its strength, appearance, and permeability. Rusted iron does not hold the desirable properties of iron. The rusting of iron can lead to damage to automobiles, railings, grills, and many other iron structures.
The collapse of the Silver Bridge in 1967 and the Mianus River bridge in 1983 is attributed to the corrosion of the steel/iron components of the bridge. Many buildings made up of reinforced concrete also undergo structural failures over long periods of time due to rusting.
Rusted iron can be a breeding ground for bacteria that cause tetanus. Cuts from these objects that pierce the skin can be dangerous.
Since rusting occurs at an accelerated rate in humid conditions, the insides of water pipes and tanks are susceptible to it. This causes the pipes to carry brown or black water containing an unsafe amount of iron oxides.
#Factors that Affect the Rusting of Iron
Many factors speed up the rusting of iron, such as the moisture content in the environment and the pH of the surrounding area. Some of these factors are listed below.
Moisture: The corrosion of iron is limited to the availability of water in the environment. Exposure to rains is the most common reason for rusting.
Acid: if the pH of the environment surrounding the metal is low, the rusting process is quickened. The rusting of iron speeds up when it is exposed to acid rains. Higher pH inhibits the corrosion of iron.
Salt: Iron tends to rust faster in the sea, due to the presence of various salts. Saltwater contains many ions that speed up the rusting process via electrochemical reactions.
Impurity: Pure iron tends to rust more slowly when compared to iron containing a mixture of metals
#How can Rusting be Prevented?
Iron and its alloys are widely used in the construction of many structures and in many machines and objects. Therefore, the prevention of the corrosion of iron is very important. Some preventive methods are listed below.
Galvanization
Galvanization is the process of applying a protective layer of zinc on a metal. It is a very common method of preventing the rusting of iron.
This can be done by dipping the metal to be protected in hot, molten zinc or by the process of electroplating.
Zinc is a relatively cheap metal that sticks to steel easily. It also offers cathodic protection to the iron surface by acting as an anode. The zinc layer is corroded instead of the iron due to this.
The disadvantages of galvanization are that it only provides protection from corrosion for a limited amount of time since the zinc layer is eaten up in the process. It is not very effective in highly corrosive areas (where cadmium coating can be used instead).
Cathodic Protection
Providing the metals with an electric charge can help inhibit the electrochemical reactions that lead to rusting.
This can be done by making the iron/steel a cathode by attaching a sacrificial anode to it.
This sacrificial anode must have an electrode potential that is more negative than that of iron.
Metals that are commonly used as sacrificial anodes are magnesium, zinc, and aluminum. Once they are corroded away, they must be replaced in order to protect the iron/steel.
Coatings
Many different types of coatings can be applied to the surface of the exposed metal in order to prevent corrosion. Common examples of coatings that prevent corrosion include paints, wax tapes, and varnish.
Smaller objects are coated with water-displacing oils that prevent the rusting of the object. Many industrial machines and tools made of iron are coated with a layer of grease, which lubricates the metal to reduce friction and prevents rusting at the same time.
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Answer:
Rusting of iron refers to the formation of rust, a mixture of iron oxides, on the surface of iron objects or structures. This rust is formed from a redox reaction between oxygen and iron in an environment containing water (such as air containing high levels of moisture). The rusting of iron is characterized by the formation of a layer of a red, flaky substance that easily crumbles into a powder.
Explanation:
Conditions for Rusting of Iron
The presence of water and oxygen is essential for the rusting of iron.
Impurities in the iron, the presence of water vapor, acids, salts and carbon dioxide hastens rusting.
Pure iron does not rust in dry and carbon dioxide free air. It also does not rust in pure water, free from dissolved salts.
Metals like chromium, zinc and magnesium prevent rusting to a great extent and alkalis also help to prevent rusting.
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