Smart Teach Chemistry Section 4

1. Smart Teach Chemistry Section 4 Extraction of metals

2. Key terms • Alloy – a mixture of a metal with another metal or carbon. • Ore – Rocks that metals can be extracted from. • Oxidised/Oxidation – Gain of oxygen. • Reduced/Reduction – Loss of oxygen or oxygen being removed.

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5. Properties of metals Typical metals have a lot of physical properties in common. They: • are lustrous (shiny) • are malleable (can be bent and pressed into different shapes) and ductile (can be drawn into wires) • are hard and strong • are good conductors of heat and electricity

6. Properties of metals Aluminium, copper and iron are metals. Aluminium has a low density (This means that they are lightweight for its size.), copper is very unreactive and iron is strong when alloyed. These metals have many uses. Draw one straight line from each metal to a use of the metal.

7. Properties of metals Aluminium, copper and iron are metals. Aluminium has a low density, copper is very unreactive and iron is strong when alloyed. These metals have many uses. Draw one straight line from each metal to a use of the metal.

8. Methods of extracting metals There are two main ways of extracting metals from their ores: • reductionwith carbon • electrolysis (using electricity). The method of extraction which is most appropriate depends on the reactivity of the metal being extracted. The reactivity series of metals can be determined by comparing the reactivity of metals with other compounds, such as acids, or by carrying out displacement reactions.

9. The reactivity series and extraction The reactivity of a metal determines how it is extracted. potassium Metals above carbon in the reactivity series must be extracted using electrolysis because they need a more powerful method of extraction. increasing reactivity sodium calcium magnesium aluminium (carbon) Metals less reactive than carbon can be extracted from their ores by reduction. zinc iron lead (hydrogen) copper Copper, silver, gold and platinum can occur nativeanddo not need to be extracted. Sometimes copper needs to be extracted from an ore. silver gold platinum

10. What is reduction? Metals are often found combined with oxygen as oxides. To obtain the metal, the oxygen must be removed. The removal of oxygen from a substance is called reduction. reduction metal metal oxide (in ore) Carbon can be used to extract metals by reduction. carbon dioxide + + Iron oxide carbon  Iron + + 2Fe2O3 3C  4Fe 3CO2 In this reaction, the carbon removes oxygen from iron oxide. This occurs because carbon is more reactive than iron. The addition of oxygen to a substance is called oxidation.

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13. Exam question • (iii) Part of the reactivity series is shown. • sodium aluminium zinc iron copper •       Aluminium is found in the ore bauxite. •       Aluminium is obtained from bauxite by electrolysis.  Explain why electrolysis has to be used to obtain aluminium from bauxite.(2)

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15. Advantages of recycling metals

16. Exam question • Scrap iron can be recycled. • Explain an advantage of recycling scrap iron rather than extracting iron from iron compounds found in the Earth. • (2)

17. Answer • an explanation linking two of • Conserves reserves (1) • Reduces a stated problem of mining (1) eg reduces carbon dioxide emissions (from machinery/trucks) / Noise pollution/dust pollution • reduces scrap iron going to landfill • less energy needed/less fuel used

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