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Chapter 5 Rocks and minerals

Chapter 5 Rocks and minerals. 5.1 Rocks. 5.2 Extraction of metals from their ores. 5.3 Limestone, chalk and marble. 5.4 Weathering and erosion of rocks. 5.5 Chemical changes involving calcium carbonate. 5.6 Tests for calcium carbonate in a sample of limestone/chalk/marble. Summary.

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Chapter 5 Rocks and minerals

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  1. Chapter 5 Rocks and minerals 5.1 Rocks 5.2 Extraction of metals from their ores 5.3 Limestone, chalk and marble 5.4 Weathering and erosion of rocks 5.5 Chemical changes involving calcium carbonate 5.6 Tests for calcium carbonate in a sample of limestone/chalk/marble Summary Concept map Chapter 5 Rocks and minerals

  2. 5.1 ROCKS WHAT ARE ROCKS AND MINERALS? 5.1 Rocks

  3. AROCKis a solid mass of a mineral or a mixture of minerals. AMINERALis a naturally occurring solid with a definite crystalline structure and chemical composition. 5.1 Rocks

  4. Figure 5.2 Quartz is a mineral. 5.1 Rocks

  5. Figure 5.3 The rock granite contains 3 minerals: quartz, feldspar and mica. 5.1 Rocks

  6. TYPES OF ROCKS Rocks are divided into three types according to their origin. Sedimentary rocks Igneous rocks Metamorphic rocks 5.1 Rocks

  7. USES OF MINERALS Graphite is used to make ‘pencil lead’. Rock salt is used in cooking. Figure 5.8 Some uses of minerals. 5.1 Rocks

  8. Jade is a gemstone used in jewellery. Marble is used as floors in commercial buildings. Figure 5.8 Some uses of minerals. 5.1 Rocks

  9. Gold is used in jewellery. Figure 5.8 Some uses of minerals. 5.1 Rocks

  10. Figure 5.9 Bauxite - the main ore of aluminium. It is mostly aluminium oxide. MINERALS AND ORES An ORE is a mineral from which a constituent (usually a metal) can be profitably extracted. 5.1 Rocks

  11. Figure 5.10 Copper pyrite - the main ore of copper. It is mostly copper iron sulphide. 5.1 Rocks

  12. Figure 5.11 Haematite - the main ore of iron. It is mostly iron(III) oxide. 5.1 Rocks

  13. Figure 5.12 Galena - the main ore of lead. It is mostly lead(II) sulphide. 5.1 Rocks

  14. Mixed with Mixed with Impurities Minerals 5.2 EXTRACTION OF METALS FROM THEIR ORES EXTRACTING METALS Metal ore Compound of the metal 5.2 Extraction of metals from their ores

  15. To obtain a pure metal from its ore 1. Mining of the ore 2. Concentrating the ore 3. Extraction of the metal from the concentrated ore 4. Purification of the impure metal 5.2 Extraction of metals from their ores

  16. extract dig up concentrate purify concentrated ore, with little waste ore in the ground pure metal ore mixed with waste rock etc. impure metal Figure 5.13 Extracting a metal from its ore. 5.2 Extraction of metals from their ores

  17. heat iron(III) oxide + carbon iron + carbon dioxide (coke) electrolysis aluminium oxide aluminium + oxygen Extraction of iron from haematite Extraction of aluminium from bauxite 5.2 Extraction of metals from their ores

  18. LIMITED RESERVES OF NATURAL RESOURCES Limited Non-renewable WE MUST USE MATERIALS WISELY! 5.2 Extraction of metals from their ores

  19. 5.3 LIMESTONE, CHALK AND MARBLE ROCKS CONTAINING CALCITE Figure 5.14 Limestone. 5.3 Limestone, chalk and marble

  20. Figure 5.15 Chalk. 5.3 Limestone, chalk and marble

  21. Figure 5.16 Marble. 5.3 Limestone, chalk and marble

  22. Limestone, chalk and marble are common rocks. In common Contain the same mineral calcite Different Appearance Hardness 5.3 Limestone, chalk and marble

  23. HOW WERE LIMESTONE, CHALK AND MARBLE FORMED? 1. Millions of years ago, oceans were filled with sea creatures having shells. 2. When they died, the remains built up a thick deposit on ocean beds. 3. These deposits were under great pressure and turned into limestone or chalk. 4. As the Earth’s crust moved, these mineral deposits were pushed upward and formed hills. 5.3 Limestone, chalk and marble

  24. Movement of the Earth’s crust raised the limestone out of the sea floor to form this hill by the seashore. 5.3 Limestone, chalk and marble

  25. Formation of limestone. 5.3 Limestone, chalk and marble

  26. USES OF LIMESTONE Figure 5.19 A footpath made of limestone. 5.3 Limestone, chalk and marble

  27. Figure 5.20 Limestone is a raw material for making cement. 5.3 Limestone, chalk and marble

  28. Figure 5.21 The outside wall of this building is made of glass. Limestone is used in glass making. 5.3 Limestone, chalk and marble

  29. buildings and roads steel concrete glass cement limestone paper mortar slaked lime neutralizes acidic soil Figure 5.22 Uses of limestone. 5.3 Limestone, chalk and marble

  30. 5.4 WEATHERING AND EROSION OF ROCKS WEATHERING AND EROSION WEATHERING of rocks is the slow process (usually over thousands of years) in which exposed rocks are broken down into smaller pieces. Weathering occurs through the actions of water, wind, air and changes in temperature. 5.4 Weathering and erosion of rocks

  31. EROSION of rocks is the slow process in which weathered rock pieces are transported away by gravity, wind and water. Erosion also refer to the process which involves weathering of rocks and transportation of weathered rock pieces to another place. 5.4 Weathering and erosion of rocks

  32. Figure 5.23 The Great Wall of China has been continuously weathered during the past 2200 years. 5.4 Weathering and erosion of rocks

  33. Figure 5.24 Wind erosion caused this unusual limestone formation. 5.4 Weathering and erosion of rocks

  34. Figure 5.24 This gorge was formed by eroding action of the river. 5.4 Weathering and erosion of rocks

  35. TYPES OF WEATHERING Physical weathering Chemical weathering 5.4 Weathering and erosion of rocks

  36. PHYSICAL WEATHERING Weathering by temperature changes 1. Rocks get hot and expand in daytime ROCKS BREAK! 2. Cool down and contract quickly at night 5.4 Weathering and erosion of rocks

  37. Figure 5.25 Rocks in deserts are badly weathered, partly due to big day-and-night temperature changes. 5.4 Weathering and erosion of rocks

  38. Weathering by frost action Rainwater gathers in crack Eventually a piece of rock breaks off Ice The crack gets bigger Rock 。 Temperature falls below 0 C Figure 5.26 Expanding ice breaks rocks. 5.4 Weathering and erosion of rocks

  39. Weathering by abrasion WAVES Breaking down and grinding away of rocks WIND FAST MOVING STREAMS 5.4 Weathering and erosion of rocks

  40. Figure 5.27 A fast-moving stream acts like sandpaper to grind rocks. 5.4 Weathering and erosion of rocks

  41. carbon dioxide carbonic acid water carbonic acid calcium hydrogencarbonate calcium carbonate CHEMICAL WEATHERING Attack by acid + + 5.4 Weathering and erosion of rocks

  42. Calcium hydrogencarbonate is soluble in water and thus the limestone is slowly worn away. 5.4 Weathering and erosion of rocks

  43. Figure 5.28 A sinkhole in limestone area. 5.4 Weathering and erosion of rocks

  44. Figure 5.29 This limestone statue has been chemically weathered by rain. 5.4 Weathering and erosion of rocks

  45. Attack by oxygen Oxygen in air can attack some rocks, especially those containing iron. This causes the rock to wear away slowly. Figure 5.30 Air can oxidize rocks containing iron, causing a brown colour. 5.4 Weathering and erosion of rocks

  46. break down into and become SOIL Rocks Soil Smaller particles 5.4 Weathering and erosion of rocks

  47. Figure 5.32 Soil is a mixture of small rock particles, air, water and humus. 5.4 Weathering and erosion of rocks

  48. gentle heating strong heating 5.5 CHEMICAL CHANGES INVOLVING CALCIUM CARBONATE THERMAL DECOMPOSITION OF CALCIUM CARBONATE No visible change Calcium carbonate Carbon dioxide Calcium oxide 5.5 Chemical changes involving calcium carbonate

  49. test tube holder roaring non- luminous flame calcium carbonate Bunsen burner Figure 5.33 Heating calcium carbonate strongly. 5.5 Chemical changes involving calcium carbonate

  50. Water Calcium oxide is commonly known as quicklime. Heat Calcium oxide + Calcium hydroxide + (Slaked lime) 5.5 Chemical changes involving calcium carbonate

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