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Question 1 - 15
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Why is the systematic classification of materials of importance to the material scientist
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The systematic classification of materials allows the ‘material scientists’ to better understand the properties and characteristics of the material. Such as the three types of classification (Solid, Liquid and Gas)
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Factors of classification can include
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The chemical composition
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Mode of occurrence in nature
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Refining and Manufacturing process to which it must be subjected before it gains economic importance
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its internal structure (atomic and crystalline)
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The industrial uses which materials are put
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List and briefly discuss the significance of three factors that are used as bases of systems of materials classifications
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Classification of Metals and Non-metals
- Better understanding of distinct properties, including its chemical reactivity and effectively utilize them on their characteristics
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Chemical composition
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Important to maintain potential hazards because of the classification system (Knowing what is dangerous because they are bunched together)
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Understanding different behaviors and characteristics
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Mechanical properties
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Classifying by the materials strengths, stiffness, toughness, hardness as well as ductility
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Distinguish between elements, compounds, and mixtures
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Elements
- A chemically simple substance made up of atoms, all of the same kind
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Compounds
- A compound is formed when two or more elements chemically combine in fixed proportions by weight
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Mixture
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A mixture is formed when two or more pure substance (element or compound) are mechanically mixed together in any proportion
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Distinguish between metals and non-metals in terms of their characteristics properties and uses
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Metals
- Solid at room temperatures, malleable and ductile to some degree, metals are also a good thermal and electrical conductors, metals can also usually form alloys
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Non-metals
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Non-metals can be solid, liquid and gas, often brittle and dull as solids, they usually are non conductors, non-metals on the other hand cannot form alloys but can chemically combine in making compounds
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Briefly explain the meaning of the following terms as they relate to metals : alloy ; clad metal ; coated metal ; non-ferrous ; sintered metal. Give examples to illustrate your answer
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Alloy
- A alloy is when a substance that combines more than one metal or mixes a metal with non metallic elements, (Brass, combination of copper and zinc)
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Clad metal
- Clad metal is a composite of materials bonded by two more metals together, creating a layered structure where each metal contributes specific properties to the overall material, This was used to improve corrosion survivability and enhanced conductivity ( for example coins created or covered by nickel or copper)
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Coated Metal
- Coated metals are designed to survive or to protect the surface from rust, corrosion, dirt and debris(for example galvanized stee where little scratches are repaired on its own because of the coating)
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Non ferrous metals
- Non ferrous metals are metals that does not contain significance amounts of iron, not magnetic (common materials such as copper, aluminum, lead and zinc are all non ferrous metals)
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Sintered metals
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Sintered metals are created through the process of ‘sintering’ this process is when powered metals are compacted and heated below its melting point, this process fuses the materials to form a solid mass with strong strengths and desired properties (steel gears and bearings used in an automotive)
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Distinguish between organic and biological materials in terms of their characteristics structures and properties
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Organic Materials
- Organic materials are usually derived mainly from carbon (examples such as crude oil, natural gas, coal, wood and rubber)
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Biological materials
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Biological materials comes from/ derived or produced by biological organisms such as plants and animals(examples such as a bone from an animal and wood from plants or stem)
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Classify between the following materials as either naturally-occurring or manufactured : polythene, coal, native copper, mild steel, timber, dimension stone, natural rubber, bone leather, limestone, diatomaceous earth, Justify your answers
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Naturally occurring materials
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Coal
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native copper
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Timber
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Natural rubber
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Dimension stone
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Limestone
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Diatomaceous earth
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All materials listed above can be found any where around the earth, and are not manufactured within a factory of any sorts
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Manufactured materials
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Polythene
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Mild steel
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Bone leather
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Materials in this list are all manufactured within a factory or has been changed through man made instruments
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What is an inorganic material? Briefly discuss the important features of any tow groups of inorganic materials
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An inorganic material are materials that have no trace of carbon(examples of these are gases such as oxygen, nitrogen or silicone)
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Two groups of inorganic materials includes, Ionic compounds and molecular materials
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The importance of these two groups of inorganic materials are that they form a basis of many substances found in nature
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Outline the effects that tanning has on animal hide
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tanning animal hide transforms it from a perishable material into durable leather by chemically altering the collagen fibers in the skin, making it resistant to decay, more pliable (for example furniture that involves removing hair from and cleaning the hide)
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. Explain the important differences between igneous and sedimentary rocks in terms of their modes of formation and characteristic structures. Use examples to illustrate your answer
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Igneous Rocks
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Formed from melted rocks that has been cooled and solidified (Magma or Lava)
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characteristics of Igneous Rocks is:
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Does not include any fossil deposits
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Includes more than one mineral deposits
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Can be either glassy or coarse
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Usually do not react with acids
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Mineral deposits may be available in forms of patches and various sizes
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Sediment Rocks
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Sediment rocks are formed from accumulation and lithification of smaller particles hence ‘sediments’, such as sand, silt and other organic materials(plants and animals) that settle (process in which sediments gradually sink and deposit at the bottom of a bod of water) out of water or air, or precipitation of minerals from water
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Characteristics of Sediment Rocks:
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May contain fossils of plants and animals
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Made up of layers that can be distinguished through colour, colour is predetermined by the contents of the layers
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Sedimentary rocks can be either chemical, organic or inorganic
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Sedimentary rocks can contain oil, natural gas, coal, phosphates, salt deposits, ground water and other natural resources
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layers of sedimentary rocks reflect conditions when the sediment was deposited
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What are metamorphic rocks and why are they often termed secondary rocks?
- Metamorphic rocks are rocks that have transformed from their original state (igneous or sediment) due to the intense heat and pressure deep within the crust of the earth, They are often called secondary rocks because they are formed through pre existing rocks (derivative of another rock that underwent metamorphism)
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What are pozzolanic materials?
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Pozzolanic materials are solid waste materials that react with calcium hydroxide to create compounds with cementitious properties, pozzolanic materials can be either natural or artificial
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What is the essential feature of ceramic material?
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Essential features of ceramic materials include:
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Hardness
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Difficult to bend and compress
- resistant to scratching and rubbing
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Brittleness
- Can easily break if impacted suddenly
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Chemical stability
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resistant to chemical reactions with other materials
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useful for storing and transporting corrosive substances
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Gold and silver often occur in their free states in nature which iron has to be extracted from its ores. How is this explainable in terms of the fundamental properties of these metals?
- Because gold and silver are usually significantly less reactive compared to iron, from this they can not steadily combine with other elements to form compounds, Gold and Silver is classified as ‘Noble metals’ because of their low chemical reactivity causing them to be more resistant towards corrosion and oxidation compared to iron
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“Some inorganic materials like stone and coal are stronger than most metals”. Criticise this statement, explaining why many articles normally made from metal could not and should not made from stone or coal
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Stone and metals are far less weaker compared to metals, they lack tensile strength, ductility and toughness, for example stone is strong under compression however it is brittle and lack flexibility same for coal, which is impractical.
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Comparing to metals, they are far more malleable and tough, with more ductility. In contrast metals are easily welded or forged into many shapes, which is ideal in creating articles, Metals can also easily absorb impacts without breaking, unlike coal and stones.
- Some metals in the other hand are more resistant towards corrosion, being able to thrive and resist environmental damage for example ‘Stainless steel’, which stone and coal may easily degrade from harsh conditions.
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