Extraction of metals The History of Metals. Metals have been used by people for many thousands of years. Gold and silver‚ found as native metal‚ were used both as jewellery and as a status symbol - nothing new there. These metals were known in the Stone Age‚ but gold and silver are too soft to be used as tools. The first really useful metal to be discovered was bronze. This began the Bronze Age. Bronze was used extensively for tools and weapons in Asia and Africa from 4‚500 B.C. (6‚500 years
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Chemical Prperties of Metals Most metals are chemically reactive‚ reacting with oxygen in the air to form oxides over changing timescales (for example iron rusts over years and potassium burns in seconds). The alkali metals react quickest followed by the alkaline earth metals‚ found in the leftmost two groups of the periodic table. Examples: 4Na + O2 → 2Na2O (sodium oxide) 2Ca + O2 → 2CaO (calcium oxide) 4Al + 3O2 → 2Al2O3 (aluminium oxide) The transition metals take much longer to
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Transition Metals 1a) The d-orbitals of a free transition metal atom or ion are degenerate (all have the same energy.) However‚ when transition metals form coordination complexes‚ the d-orbitals of the metal interact with the electron cloud of the ligands in such a manner that the d-orbitals become non-degenerate (not all having the same energy.) The way in which the orbitals are split into different energy levels is dependent on the geometry of the complex. Crystal field theory can be used to predict
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Case Study Finance - EDHEC MBAUnited Metal | | Background We refer to the case in the finance textbook for the details. Throughout our efforts in determining the right decision for United Metal‚ our team decided to calculate the difference between the ‘Make’ or ‘Buy’ options‚ using the numbers given in the case. However‚ in order to determine the net present value (NPV) and make appropriate recommendations‚ a risk adjusted discount rate (rate-of-return or ‘r’) needs to be incorporated.
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Schools have Metal Detectors? Have you ever felt violated‚ disrespected and dishonored to the point of no return? Many students around the world feel such a way every day. According to a 2002 National School Board Association report‚ 10.1 percent of school districts nationwide implement the use of metal detectors. Are metal detectors even effective? Why should students be forced to cooperate with a violation of their rights? High Schools around the world should not employ the use of metal detectors
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Extrusion is the process by which a block/billet of metal is reduced in cross section by forcing it to flow through a die orifice under high pressure. • In general‚ extrusion is used to produce cylindrical bars or hollow tubes or for the starting stock for drawn rod‚ cold extrusion or forged products. • Most metals are hot extruded due to large amount of forces required in extrusion. Complex shape can be extruded from the more readily extrudable metals such as aluminium. * The products obtained are also
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Tony Nguyen Honors Chemistry Period 7 9/17/13 The Density of Metals Lab BACKROUND: Density is a constant relationship between the mass and volume of a specific type of matter. Measurements of both mass and volume can be obtained for a metal sample. The relationship can be shown graphically by plotting the volume of a sample on the horizontal x-axis and the mass of the sample along the vertical y-axis. Plotting the values for several samples‚ a linear relationship can be seen for a density (slope=density)
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A metal is defined as an opaque shiny element which possesses properties such as malleability and ductility. Malleable meaning that they can be hammered into shapes and ductile meaning they can be drawn into wires. They are also very strong and posses high tensile strength and are good conductors of heat and electricity. Metals are shiny‚ and also have high densities. Metals are a very important and significant part of chemistry. However‚ their importance is not just limited to chemistry; they are
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fear of terrorism set out by the event of 9/11 made it a more fear-driven world with growing minds of over analytical‚ blind‚ ignorant and assumable citizens‚ finger-pointing at others. But Jose Saramago’s Blindness shows the possibility of fear molding our society. An epidemic of a bright‚ white blindness affecting all people‚ such brightness that no one would see anything but the white brightness itself‚ the novel uses this metaphorically as that we choose to ignore so much of the misery that goes
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Exam Objectives for Installing Windows XP Professional (Exam 70-270) Perform and troubleshoot an attended installation of Windows XP Professional. Perform and troubleshoot an unattended installation of Windows XP Professional. o Install Windows XP Professional by using Remote Installation Services (RIS). o Install Windows XP Professional by using the System Preparation Tool. o Create unattended answer files by using Setup Manager to automate the installation of Windows XP Professional.
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