Cambridge (CIE) IGCSE Chemistry Extraction of Metals PDF

Head to www.savemyexams.com for more awesome resources Cambridge (CIE) IGCSE Your notes Chemistry Extraction of Metals Contents Extraction of Metals Extraction of Iron from Hematite Extraction of Aluminium from...

Head to www.savemyexams.com for more awesome resources Cambridge (CIE) IGCSE Your notes Chemistry Extraction of Metals Contents Extraction of Metals Extraction of Iron from Hematite Extraction of Aluminium from Bauxite Page 1 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Extraction of Metals Your notes Extraction of Metals The Earth’s crust contains metals and metal compounds such as gold, copper, iron oxide and aluminium oxide Useful metals are often chemically combined with other substances forming ores: A metal ore is a rock that contains enough of the metal to make it worthwhile extracting They have to be extracted from their ores through processes such as electrolysis, using a blast furnace or by reacting with more reactive material In many cases the ore is an oxide of the metal, therefore the extraction of these metals is a reduction process since oxygen is being removed Common examples of oxide ores are iron and aluminium ores which are called hematite and bauxite respectively Unreactive metals do not have to be extracted chemically as they are often found as the uncombined element This occurs as they do not easily react with other substances due to their chemical stability They are known as native metals and examples include gold and platinum which can both be mined directly from the Earth’s crust The position of the metal on the reactivity series influences the method of extraction Those metals placed higher up on the series (above carbon) have to be extracted using electrolysis Metals lower down on the series can be extracted by heating with carbon The Extraction Method Depends on the Position of a Metal in the Reactivity Serie Metal Method of Extraction Most reactive Potassium Extracted by electrolysis of molten chloride or molten oxide Large amount of electricity required so expensive process Sodium Page 2 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Lithium Your notes Calcium Magnesium Aluminium Carbon Zinc Extracted by heating with reducing agent such as carbon or carbon monoxide Iron Hydrogen Copper Found as pure elements (copper may have to be extracted from it's ore by heating with carbon or hydrogen) Silver Gold Least reactive Page 3 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Extraction of Iron from Hematite Your notes Extraction of iron from hematite Iron is extracted in a large container called a blast furnace from its ore, hematite Modern blast furnaces produce approximately 10,000 tonnes of iron per day The blast furnace Page 4 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Page 5 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Diagram showing the carbon extraction of iron The raw materials: iron ore (hematite), coke (an impure form of carbon), and limestone are added into Your notes the top of the blast furnace Hot air is blown into the bottom Zone 1 Coke burns in the hot air forming carbon dioxide The reaction is exothermic so it gives off heat, heating the furnace carbon + oxygen → carbon dioxide Zone 2 At the high temperatures in the furnace, more coke reacts with carbon dioxide forming carbon monoxide Carbon dioxide has been reduced to carbon monoxide carbon + carbon dioxide → carbon monoxide Zone 3 Carbon monoxide reduces the iron(III) oxide in the iron ore to form iron This will melt and collect at the bottom of the furnace, where it is tapped off iron(III) oxide + carbon monoxide → iron + carbon dioxide Limestone (calcium carbonate) is added to the furnace to remove impurities in the ore The calcium carbonate in the limestone thermally decomposes to form calcium oxide calcium carbonate → calcium oxide + carbon dioxide The calcium oxide formed reacts with the silicon dioxide, which is an impurity in the iron ore, to form calcium silicate This melts and collects as a molten slag floating on top of the molten iron, which is tapped off separately calcium oxide + silicon dioxide → calcium silicate Examiner Tips and Tricks Page 6 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources For Core students, the symbol equations are not needed for the different reactions involved in the extraction of iron from hematite. Your notes Equations for extraction of iron from hematite Extended tier only Zone 1 The burning of carbon (coke) to provide heat and produce carbon dioxide: C (s) + O2 (g) → CO2 (g) Zone 2 The reduction of carbon dioxide to carbon monoxide: CO2 (g) + C (s) → 2CO (g) Zone 3 The reduction of iron(III) oxide by carbon monoxide: Fe2O3 (s) + 3CO (g) → 2Fe (I) + 3CO2 (g) The thermal decomposition of calcium carbonate (limestone) to produce calcium oxide: CaCO3 (s) → CaO (s) + CO2 (g) The formation of slag: CaO (s) + SiO2 (s) → CaSiO3 (l) Page 7 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Extraction of Aluminium from Bauxite Your notes Extraction of aluminium from bauxite Aluminium is a reactive metal, above carbon in the reactivity series Its main ore, is bauxite, which contains aluminium oxide Aluminium is higher in the reactivity series than carbon, so it cannot be extracted by reduction using carbon Instead, aluminium is extracted by electrolysis The electrolysis of aluminium Diagram showing the extraction of aluminium by electrolysis Examiner Tips and Tricks Page 8 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources If you are a Core student, you do not need to explain the process of extraction of aluminium by electrolysis. Your notes The process of aluminium extraction by electrolysis Extended tier only Bauxite is first purified to produce aluminium oxide, Al2O3 Aluminium oxide is then dissolved in molten cryolite This is because aluminium oxide has a melting point of over 2000 °C which would use a lot of energy and be very expensive The resulting mixture has a lower melting point without interfering with the reaction The mixture is placed in an electrolysis cell, made from steel, lined with graphite The graphite lining acts as the negative electrode, with several large graphite blocks as the positive electrodes At the cathode (negative electrode): Aluminium ions gain electrons (reduction) Molten aluminium forms at the bottom of the cell The molten aluminium is siphoned off from time to time and fresh aluminium oxide is added to the cell Al3+ + 3e- → Al At the anode (positive electrode): Oxide ions lose electrons (oxidation) Oxygen is produced at the anode: 2O2- → O2 + 4e- The overall equation for the reaction is: 2Al2O3 → 4Al + 3O2 The carbon in the graphite anodes reacts with the oxygen produced to produce CO2 C (s) + O2 (g) → CO2 (g) As a result the anode wears away and has to be replaced regularly A lot of electricity is required for this process of extraction, this is a major expense Page 9 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Examiner Tips and Tricks Use OIL RIG to remember whether oxidation or reduction has occurred at the electrodes: Page 10 of 10 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers