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The existence of metals often plays a crucial role in our survival, even if we are unaware of them. Our reliance on metals has been strong since the industrial era. From buildings to jewelry, we use them for everything. But where do we acquire these metals and how are they made? Let's look into the occurrence of metal in more detail.
Metals are found in the earth's crust, and it is a good place to extract them from by various processes such as metallurgy. Metallurgy is the process of extracting metals from ores. Mining is the most common method of extracting metals from the earth.
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Metals are mostly found in nature in a mixed condition, however, they can also be found in a free state. A native metal is one that can be found in its pure form or as part of an alloy in its natural state. Most metals are susceptible to natural processes such as oxidation and corrosion. As a result, only non-reactive metals such as gold, silver, platinum, and others are discovered in their native or free condition. Most metals are obtained as compounds, which must be filtered to remove contaminants before being employed in various applications.
Read more : Material Properties
Redox Reactions
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Have you ever noticed how iron objects rust? I am sure we've all witnessed the rusting of an iron object at some point or another. It's an example of a redox reaction involving oxidation and reduction. Many biological and scientific phenomena are based on redox reactions.
Some examples of oxidation and reduction reactions, often known as redox processes, are Colors fading from your clothes, and other types of fuels or combustible substances, such as wood and coal, burned to generate energy for commercial, home, and transportation needs.
Redox Reactions as a Classical Idea
In addition, redox reactions are used in a variety of industries, including biological, industrial, medicinal, metallurgical, and agricultural industries.
Some industrial processes which are examples of redox reactions are
- Electroplating
- Extraction of metals such as aluminium
- Manufacturing of chemical compounds such as caustic soda
- Bleaching of wood pulp
- Metal corrosion
- Battery operation, and many more
Many environmental issues, such as the ozone hole, are tied to the redox reaction phenomena.
Corrosion
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Corrosion is a chemical reaction that causes metals to corrode. Corrosion is a natural phenomenon that occurs when chemically active metals are exposed to a moist environment. Rusting and corrosion are not the same things, contrary to popular assumptions.
The process of rusting occurs when the iron is exposed to the elements. Corrosion is an oxidation reaction in which the water or moisture on the metal's surface oxidizes with the oxygen in the atmosphere. Because iron is a structural material used in construction, bridges, buildings, rail transportation, ships, and other applications, it is prone to corrosion.
Ores
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All of the ores are minerals but all the minerals are not ores. Minerals that contain metals are known as ore. Metals are extracted using a variety of ways. Carbon is used as a reducing agent in the melting of common metals like iron. Electrolysis used to remove few metals that don't have an economically viable reducing agent, such as aluminium and sodium. Sulphide ores are heated in the air to convert them to oxides rather than being converted straight to metal.
The Electrolysis Process
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Electrolysis is the decomposition of a specific element under the influence of an electric current, to put it simply. Sir Humphrey Davey performed the first electrolysis experiment in 1808. This experiment gave new insights into the behavior of specific elements and how they differ from compounds and ions.
Matrix or Gangue
The gangue or matrix is a rocky, earthy, or sandy substance found with ores that are undesired and commercially useless. These are the contaminants that will be filtered away later.
Extraction of Metals
The discovery of metals in nature is merely the first step; these metals must also be extracted. The process of obtaining metals is known as metallurgy. The concentration of ores is the first step in the extraction of metals.
Ores Concentration
There are a lot of contaminants in the ores that need to be filtered out. Concentration is the filtering of these contaminants from ores. Gravity separation, hydraulic washings, and the froth flotation process are all options for concentration.
Metals with a high level of reactivity
Metals at the top of the reactivity scale, such as sodium, magnesium, calcium, and others, are too reactive to be extracted from their compounds by heating with carbon. To obtain such metals, an electrolytic reduction is performed.
Metals with a medium level of reactivity
Metals in the center of the reactivity scale, such as lead, zinc, copper, and others, are moderately reactive and typically appear as carbonates or sulphides. Heat is used to transform sulphide ores into oxides in the presence of abundant air.
Roasting is a technique that allows sulphur impurities to escape as gas.
Calcination is used to remove carbonate and moisture impurities from carbonated ores. Calcination is a method of converting ore into oxides by rapidly heating it in the presence of excess air.
Metals with a low reactivity
Metals that aren't extremely reactive are grouped together at the bottom of the reactivity scale. By heating them alone, these metals can be converted to metals. Mercury, for example, is extracted from its ore, cinnabar (HgS), using a heating process. Heating can also be used to extract copper from its sulphide ore (Cu2S).
Read more : Important notes on metals and non-metals
Frequently Asked Questions (FAQs)
Ques: Which metal is the most reactive?
Iron
Mercury
Sodium
Potassium (1 mark)
Ans: Option ‘C' is the correct answer. The most reactive metal is sodium (Na). It is kept in kerosene to prevent it from reacting with oxygen and moisture in the air.
Ques: Which of the metals below corrodes quickly?
Gold (Au)
Silver (Ag)
Copper (Cu)
Iron (Fe) (1 mark)
Ans: Option ‘D' is the correct answer. Iron corrodes faster than other metals, resulting in iron oxide. In the presence of CO2, as well as a salt solution, the corrosion or rusting of iron is accelerated.
Ques: How do metals appear in nature? (1 mark)
Ans: Metals can be found in nature in both free and mixed forms. Metals are mostly obtained from the Earth's crust. Some metals, such as gold, silver, and mercury, are found in the free state of the earth's crust, while others, due to their higher reactivity, are found in the form of their compounds.
Ques: How are metals discovered and extracted? (1 mark)
Answer: The majority of metals are mined from ores in the Earth's crust. An ore is a type of rock that contains enough of metal or its combination to make it eventually worthwhile to extract the metal from it. Metal oxide ores are widespread, but sulphide and carbonate ores are also frequent.
Ques:What is the origin of metals in the Earth's crust? (1 mark)
Answer: Metals can be found in the Earth's crust. These pure metals are typically found in minerals found in rocks. You're more likely to locate metals if you dig into the soil and/or collect rocks because that's where they're located in nature. Compounds, sometimes known as minerals, are formed by metals.
Ques: Give two examples of how metals exist naturally. (1 mark)
Ans: Metals are found in nature based on their reactivity. Metals with low reactivity exist in their natural condition. Gold (Au), for example, and silver (Ag). Moderately reactive metals found primarily as oxides, sulphides, and carbonates in the earth's crust.
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