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1 of 36© Boardworks Ltd 2006. 2 of 36© Boardworks Ltd 2006.

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Presentation on theme: "1 of 36© Boardworks Ltd 2006. 2 of 36© Boardworks Ltd 2006."— Presentation transcript:

1 1 of 36© Boardworks Ltd 2006

2 2 of 36© Boardworks Ltd 2006

3 3 of 36© Boardworks Ltd 2006 What materials are used in buildings? How are materials from the Earth used in construction?

4 4 of 36© Boardworks Ltd 2006 Where do building materials come from? glass is made from sand and limestone bricks are made from clay cement is made from limestone or clay. Buildings are constructed using materials from the Earth. Some ‘cut rocks’, including granite, marble and limestone, make excellent building materials. Changing or combining rocks from the Earth provides other useful materials:

5 5 of 36© Boardworks Ltd 2006 How are rocks formed in nature? Metamorphic rocks are rocks changed by heat or pressure. Marble is a metamorphic rock that started as limestone. It is harder than limestone. Igneous rocks are formed from cooled magma from the inside of the Earth. These rocks are very hard and difficult to shape. Granite is a type of igneous rock. Sedimentary rocks are made from deposited sediments. They are relatively soft and easy to shape. Limestone and clay are sedimentary rocks. The hardness and uses of a rock depend on how it is formed.

6 6 of 36© Boardworks Ltd 2006 Classifying rocks

7 7 of 36© Boardworks Ltd 2006 Cement is used as a binder in concrete and mortar. What is cement? It is made by heating limestone or clay and adding gypsum (a compound from limestone). This mixture is then ground into a powder. Mortar is made from cement, water and sand. It is used in bricklaying and stonework. An even layer of mortar is spread between the bricks or stones to hold them firmly together. After the powder is mixed with water, it will harden to form a strong glue.

8 8 of 36© Boardworks Ltd 2006 How is concrete made? Concrete is made from sand, cement and water but it is harder than mortar because it also contains gravel. What is the word equation for making concrete? Concrete is harder than mortar. It is sometimes described as an artificial rock. It is used for the foundations of buildings and for large structures, such as car parks. cement sand water concrete + +  gravel +

9 9 of 36© Boardworks Ltd 2006 What is reinforced concrete? Although concrete is a very hard material, it is not very flexible. This means that when it is stretched it can break. Concrete has a low resistance to tension forces. Steel rods are used to increase the strength and flexibility of concrete. This is called reinforced concrete. This material can support 300 to 500 times the combined mass of steel and concrete it is made from. Reinforced concrete has many uses, including lamp-posts, railways and as a structural material to support buildings.

10 10 of 36© Boardworks Ltd 2006 Building materials

11 11 of 36© Boardworks Ltd 2006

12 12 of 36© Boardworks Ltd 2006 What is limestone? Limestone is an attractive pale yellow or grey stone. Limestone is used during the production of other building materials including: cement concrete It is also used to extract impurities from iron in a blast furnace, which produces a useable metal from iron ore. mortar glass Blocks of cut limestone are used as a material for buildings and statues.

13 13 of 36© Boardworks Ltd 2006 How is limestone formed? Limestone is a sedimentary rock. It is made over millions of years by the compression of shells and skeletons. There are different types of limestone, all containing a high percentage of calcium carbonate (CaCO 3 ). It is quarried from the Earth for use as a building material. Marble, a metamorphic rock formed from limestone, also contains calcium carbonate. It is more expensive than limestone but erodes more slowly. Limestone can become eroded by rainwater.

14 14 of 36© Boardworks Ltd 2006 Formation of limestone

15 15 of 36© Boardworks Ltd 2006 When limestone is heated strongly, a chemical reaction takes place. Calcium carbonate breaks down and forms calcium oxide and carbon dioxide. This type of reaction is called thermal decomposition. Limestone is a valuable material because it can be used as the starting point for many other materials. calcium carbonate calcium oxide carbon dioxide  + What is thermal decomposition? A lime kiln is often used for this reaction. The limestone is heated to 900 °C. This method has been used for centuries. What is the word equation for this reaction?

16 16 of 36© Boardworks Ltd 2006 magnesium carbonate magnesium oxide carbon dioxide  + What about other metal carbonates? Other metal carbonates can decompose in a similar way to calcium carbonate, when they are heated. metal carbonate metal oxide carbon dioxide  + What products are formed when copper carbonate decomposes on heating? The general equation for the thermal decomposition of a metal carbonate is: For example, when magnesium carbonate is heated it breaks down to form magnesium oxide and carbon dioxide.

17 17 of 36© Boardworks Ltd 2006 Is this a balanced reaction? During a chemical reaction, atoms are not created or destroyed. This means that the numbers of atoms on both sides of a balanced symbol equation are always the same. calcium carbonate calcium oxide carbon dioxide CaCO 3 CaOCO 2   = number of atoms before reaction number of atoms after reaction element calcium carbon oxygen

18 18 of 36© Boardworks Ltd 2006 Thermal decomposition

19 19 of 36© Boardworks Ltd 2006 The chemical name for slaked lime is calcium hydroxide. How is slaked lime made? calcium oxide water calcium hydroxide  + What is the word equation for this reaction? Uses of slaked lime include glass manufacture and neutralization of the effects of acid rain. Quicklime is used as an industrial drying agent and to make slaked lime. Calcium oxide, a product of the thermal decomposition of limestone, is also called quicklime. Slaked lime is made by adding water to quicklime.

20 20 of 36© Boardworks Ltd 2006 Why does carbon dioxide turn limewater cloudy? Fully dissolving calcium hydroxide in water forms limewater. Limewater is used to test for carbon dioxide. When carbon dioxide gas is bubbled through limewater, the limewater becomes cloudy. The carbon dioxide reacts with calcium hydroxide to form calcium carbonate and water. The solid calcium carbonate is held in suspension, which gives the limewater a cloudy appearance. What is the word equation for this reaction? calcium carbonate calcium hydroxide (aq) carbon dioxide  ++ water

21 21 of 36© Boardworks Ltd 2006 Summary of uses of limestone products Slaked lime, calcium hydroxide, is used to make the building materials mortar and glass. Slaked lime is alkaline. It can be sprayed on agricultural fields to reduce soil acidity and on lakes to neutralize the effects of acid rain. Quicklime, calcium oxide, is used in making steel and as an industrial drying agent. It can be mixed with water to form slaked lime. Limewater is made by fully dissolving slaked lime in water. It is often used to test for carbon dioxide. This is because limewater turns cloudy in the presence of carbon dioxide. The products of limestone have many uses.

22 22 of 36© Boardworks Ltd 2006 Limestone and its products can be involved in various useful chemical reactions: Summary of limestone chemistry calcium oxide water calcium hydroxide  + calcium carbonate calcium oxide carbon dioxide  + thermal decomposition of limestone production of slaked lime using limewater to test for carbon dioxide. calcium carbonate calcium hydroxide (aq) carbon dioxide  ++ water

23 23 of 36© Boardworks Ltd 2006 How does quarrying affect the environment? Limestone is an essential building material. Millions of kilograms of limestone are extracted every year for use in construction and industry. However, quarrying limestone can cause environmental damage. Limestone is often found in areas of outstanding natural beauty. Quarrying can leave scars on the landscape. Explosives used in quarrying produce noise and dust. Air and noise pollution is caused by lorries transporting limestone from the quarry.

24 24 of 36© Boardworks Ltd 2006 Impacts of limestone quarrying

25 25 of 36© Boardworks Ltd 2006 Quarrying limestone

26 26 of 36© Boardworks Ltd 2006

27 27 of 36© Boardworks Ltd 2006 How is salt produced? The scientific name for table salt is sodium chloride. It has the formula NaCl. Salt is found dissolved in seawater. When the water evaporates it leaves deposits of salt. Ancient oceans have deposited salt in salt beds or underground rocks. These can be mined and processed. Seawater and rock salt can be used to make table salt.

28 28 of 36© Boardworks Ltd 2006 What is salt used for? In winter, rock salt can be used on roads to melt ice. This is because salt lowers the melting point of ice. The salt does not need to be pure for this use. Salt is used to flavour food. It can also be used to preserve food. White table salt is processed to remove impurities. Chemicals produced from the electrolysis of salt and brine (salt dissolved in water) are also very valuable. Sodium chloride is a useful compound.

29 29 of 36© Boardworks Ltd 2006 Electrolysis of salt water solution

30 30 of 36© Boardworks Ltd 2006 Using products from salt

31 31 of 36© Boardworks Ltd 2006 Using salt

32 32 of 36© Boardworks Ltd 2006

33 33 of 36© Boardworks Ltd 2006 Glossary (1/2) brine – Sodium chloride (table salt) dissolved in water. cement – A product of limestone. It is used as a binder in mortar and concrete. concrete – A mixture of cement, sand, gravel and water. It is used in construction. electrolysis – The use of electricity to split a compound. granite – A type of igneous rock that is harder than limestone and marble. igneous – A rock formed from cooled magna. limestone – A type of sedimentary rock containing calcium carbonate. limewater – A limestone product made by fully dissolving quicklime in water. It is used to test for carbon dioxide. marble – A type of metamorphic rock that is harder than limestone but softer than granite.

34 34 of 36© Boardworks Ltd 2006 Glossary (2/2) metamorphic – A rock changed by pressure and heat. mortar – A mixture of cement, sand and water. It is used in bricklaying and stonework. quicklime – A product of the thermal decomposition of limestone. Also called calcium oxide. reinforced concrete – A type of concrete containing steel rods for extra strength. sedimentary – A rock formed by the deposition of sediments. slaked lime – A limestone product made by adding water to quicklime. Also called calcium hydroxide. sodium chloride – The scientific name for table salt. thermal decomposition – The breakdown of a compound into simpler substances by heating.

35 35 of 36© Boardworks Ltd 2006 Anagrams

36 36 of 36© Boardworks Ltd 2006 Multiple-choice quiz


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