Resistance Aluminium naturally generates a protective oxide coating and is highly corrosion resistant. Different types of surface treatment such as anodizing‚ painting etc. can further improve this property Electrical and Thermal Conductivity Aluminium is an excellent heat and electricity. This has made aluminum the most commonly used material in major power transmission lines. Reflectivity Aluminium is a good reflector of visible light‚ which
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its ore: [pic] Because both reduction and oxidation are going on side-by-side‚ this is known as a redox reaction. Oxidising and reducing agents An oxidising agent is substance which oxidises something else. In the above example‚ the iron(III) oxide is the oxidising agent. A reducing agent reduces something else. In the equation‚ the carbon monoxide is the reducing agent. • Oxidising agents give oxygen to another substance. • Reducing agents remove oxygen from another substance. Oxidation
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EFFECTS OF CORROSION • ELECTROCHEMICAL EFFECTS • FACTORS AFFECTING CORROSION • THE RUSTING OF IRON • IDENTIFYING ANODES & CATHODES • DIAGRAMMATIC SUMMARY • DIFFERENTIAL AERATION • DIFFERENT METALS IN CONTACT • CORROSION PROTECTION • THE CORROSION OF ALUMINIUM • THEORY SUMMARY • REVISION TEST • REVISION TEST ANSWERS 2 3 4 5 6 7 7 8 9-10 11-12 13-16 17 18 19-20 21 © JAK CHEMISTRY LEVEL 3C (CHM 315109) CORROSION (CRITERION 5) INTRODUCTION: Corrosion is a general term referring to the DESTRUCTIVE
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the most common oxides on the surface of earth. Like most oxides‚ it adopts a polymeric structure. Оксидите се хемиски соединенија што содржат најмалку еден атом на кислород и еден атом од друг хемиски елемент во својата формула. An oxide /ˈɒksaɪd/ is a chemical compound that contains at least one oxygenatom and one other element[1] in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2. Most of the Earth’s crustconsists of solid oxides‚ the result of
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of alumina. 90% of the global alumina supply of around 90 million tonnes is used in aluminium production. DEFINITION The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide). The aluminium oxide must be purified before it can be refined to aluminium metal. Important Ore: BAUXITE. CONTENTS: Al2O3 - 30 -54% Rest -Silica‚ Iron Oxides and Titanium Oxides. ADVANTAGES Most economic means of obtaining alumina from bauxite. APPLICATIONS industrial
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EXTRACTION OF METALS SUMMARY Most metals exist in compounds in rocks in the Earth’s crust. Many of these ores contain oxides or sulphides of the metals. The compounds need to be reduced to produce the metals as elements. Metals are very useful to us because of their special properties. Reduction means removal of oxygen or gain of electrons. Carbon is a good chemical reducing agent because it readily combines with oxygen‚ but it is only useful for the metals below it in the Reactivity
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metal. Some unreactive metals can even be found in the native state‚ like gold. On the other hand‚ most metals are too reactive to exist on their own like aluminium‚ which has to be extracted using a method called electrolysis. And some moderately reactive metals that are in the middle of the reactivity series can be extracted using reduction of oxides like iron. Gold is not found in a mixture or
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difficult it is to extract. Thus electrolysis would be used more the more reactive and the “Blast Furnace” for the less: Metal Method of Extraction Potassium Electrolysis Sodium Electrolysis Calcium Electrolysis Magnesium Electrolysis Aluminium Electrolysis Zinc Heat with C or CO Iron Heat with C or CO Lead Heat with C or CO Copper Roasting in air Silver Occur naturally Gold Occur naturally Out of all the methods‚ native metals are the easiest to extract and require
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1 (a) In this apparatus hydrochloric acid is decomposed by passing a direct electric current through it. Chlorine and hydrogen are formed. (i) Give the name of this process in which substances‚ such as hydrochloric acid‚ are decomposed by a direct electric current. (1) electrolysis (ii) Describe what happens when a burning splint is applied to a mixture of hydrogen and air in a test tube. (2) (b) (i) Complete the sentence by putting a cross ( ) in the box next to your answer. An acid
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Chemistry : 1. Aluminium hydroxide on thermal decomposition gives aluminium oxide and water 2. Iron (iii) oxide reacts with carbon forming iron and carbonmonoxide 3. Hydrogen peroxide reacts with lead sulphide forming lead sulphate and water 4. Lithium reacts with nitrogen forming lithium nitride 5. Nickel sulphate reacts with sodium phosphate to form nickel phosphate and sodium sulphate 6. Silver oxide reacts with hydrogen peroxide to form silver ‚ water and oxygen 7
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