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Extracting Metals Prior Learning; a) Understand what happens to carbonates when they are heated b) Know that an ore contain a metal mixed with rock c)

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Presentation on theme: "Extracting Metals Prior Learning; a) Understand what happens to carbonates when they are heated b) Know that an ore contain a metal mixed with rock c)"— Presentation transcript:

1 Extracting Metals Prior Learning; a) Understand what happens to carbonates when they are heated b) Know that an ore contain a metal mixed with rock c) Know how to work safely in the laboratory Keywords: displacement, electrolysis, ore, native, reduce, coke, reduced, cast iron

2 By the end of the lesson I can:
Learning Objectives: By the end of the lesson I can: Explain where metals are obtained from. Give examples of how metals are extracted from the Earth. Metals that are less reactive than carbon can be extracted from their oxides by reduction in carbon, for example iron oxide is reduced in the blast furnace to make iron. Identify that metals less reactive than carbon can be extracted by reducing their oxides. Explain that iron is extracted in a blast furnace. •Consider and evaluate the social, economic and environmental impacts of exploiting metal ores, of using metals and of recycling metals.

3 Ores contain enough metal to make it economic to extract the metal and this changes over time.
TRUE 3. Most metals are found as compounds that require chemical reactions to extract the metal. TRUE FALSE 2. No metals are naturally found in the Earth as the metal itself.

4 Watch this demonstration on the reactivity series

5 What is this type of reaction GENERALLY called?
The Reactivity Series Metals are arranged in order of how reactive they are. A more reactive metal will displace a less reactive one from its compounds. For example, zinc will displace copper from copper sulfate to give zinc sulfate plus copper. What is the word and symbol equation? The what ??? What is this type of reaction GENERALLY called? What is the molecular formula for sulfate? zinc(s) + copper sulfate(aq) zinc sulfate(aq) + copper (s) Zn(s) + CuSO4 (aq) ZnSO4 (aq) Cu (s)

6 HOW DOES REACTIVITY CHANGE THE EXTRACTION PROCESS?
The more vigorously an element forms compounds the harder it will be to get back that element from its compounds. For example, magnesium gives out lots of heat when it combines with oxygen. This means we will have to put lots of energy back to extract magnesium from magnesium oxide and so it will be hard to extract.

7 How would you extract it?
What about gold? How would you extract it? An ore containing the element Au Would this work? Why? The element Au

8 Increasing reactivity
Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Tin Lead Copper Silver Gold Platinum Increasing reactivity Metals ABOVE CARBON, because of their high reactivity, are extracted by ELECTROLYSIS Carbon can be used to metals if it is more reactive then the metal that is to be extracted Metals BELOW CARBON are extracted by heating them with carbon in a BLAST FURNACE These LOW REACTIVITY metals won’t need to be extracted because they are SO unreactive you’ll find them on their own, not in a metal oxide. These are panned for!

9 Malachite is a mineral known as Copper Carbonate ( CuCo3)
REDOX REACTION: Extracting copper from Malachite Malachite is a mineral known as Copper Carbonate ( CuCo3) What process is needed to extract copper? When malachite is heated with Carbon, it is reduced (oxygen is removed) to leave behind copper metal. How could you do it in the lab? Copper Carbonate + Carbon Monoxide Copper metal + Carbon dioxide

10 AT THIS POINT WE WILL STOP AND CONTINUE IN PERIOD 5
Reduction by carbon Method Put on your eye protection. Add a spatula (1 cm3) of the metal oxide and carbon to your boiling tube (ratio 1:1) Clamp the boiling tube so that it is sloping. Make sure the tube is clamped close at its open end. Add a loosely fitting mineral wool plug to the open end of boiling tube. Light your Bunsen burner. Heat the tube using a hot flame. Direct the tip of the inner blue cone onto the mixture and away from the plastic on the clamps!!!! Observe what happens. Write your observation in your results table. Stop heating and allow the reaction mixture to cool. AT THIS POINT WE WILL STOP AND CONTINUE IN PERIOD 5 RESULTS TABLE REACTION OBSERVATIONS Copper oxide & Carbon Iron oxide & Carbon

11 plenary …to remove oxygen from a metal oxide
Removal of oxygen from a compound A list of elements from most to least reactive A rock containing enough metal to make it economic to extract …contain enough metal to make extraction economic Unreactive metals, found as elements in nature Metal ores are rocks that… Gold, platinum & silver… native Reactivity series ore Reduction reactions are… reduction …native metals

12 Extracting Metals Part 2
Prior Learning; a) Understand what happens to carbonates when they are heated b) Know that an ore contain a metal mixed with rock c) Know how to work safely in the laboratory Keywords: displacement, electrolysis, ore, native, reduce, coke, reduced, cast iron

13 By the end of the lesson I can:
Learning Objectives: By the end of the lesson I can: Explain where metals are obtained from. Give examples of how metals are extracted from the Earth. Metals that are less reactive than carbon can be extracted from their oxides by reduction in carbon, for example iron oxide is reduced in the blast furnace to make iron. Identify that metals less reactive than carbon can be extracted by reducing their oxides. Explain that iron is extracted in a blast furnace. •Consider and evaluate the social, economic and environmental impacts of exploiting metal ores, of using metals and of recycling metals. EXT: Explain how electrolysis works and why it is not always used

14 …continuing on Take an evaporating dish and add about 25 cm3 of sulfuric acid to it. Take your (now cool) reaction mixture and add it to the acid. Observe what happens. Write your observation in your results table. Complete word and chemical equations for your extraction.

15 Reactivity Series Type of metal Extraction process Examples
High reactivity (i.e anything above carbon) Middle reactivity (i.e. anything below carbon) Low reactivity Potassium, Sodium, Calcium, Magnesium, Aluminium ELECTROLYSIS BLAST FURNACE (heating with carbon to reduce their oxides) Zn, Fe, Sn, Pb, Cu Silver, Gold, Platinum PHYSICAL EXTRACTION

16 Which substance is being oxidised? Reduced?
Iron oxide + carbon monoxide iron + carbon dioxide What are the molecular formulas? & what do they mean? CaCO3 Fe2O3 C Chemical: Calcium Carbonate Common: Limestone Chemical: Iron (III) oxide Common: Haematite Chemical: Carbon Common: Coke

17 Teacher notes This animation illustrates the basic processes of the blast furnace and can be used to introduce students to chemical reactions on an industrial scale. It should be explained to students that the temperature in the blast furnace is increased by the blast of air. Students should be aware that the oxygen in the air causes the carbon to burn and produces more heat.

18 Blast furnace Coke + oxygen gas (forms) carbon dioxide gas C + O2 (forms) CO2 Write the chemical reactions for the following stages in the blast furnace. Hot air is blown into the blast furnace which makes the coke burn and oxidise. At high temperatures, carbon dioxide gas reacts with more coke and is reduced. The resulting gas reacts with iron (III) oxide causing it to reduce whilst the gas oxidises in a ‘redox reaction’. Carbon dioxide gas + coke (forms) carbon monoxide gas CO2 + C (forms) CO Carbon monoxide gas + iron (III) oxide (forms) iron metal + carbon dioxide gas Fe2O3 + 3CO (forms) 2Fe + 3CO2

19 Iron Mining Use you text (p41) and this video to consider and evaluate the social, economic and environmental impacts of exploiting metal ores, of using metals and of recycling metals. (6 marks)

20 Extraction, especially electrolysis, also uses lots of electricity.
Open-cast mining removes ores using explosives. It produces dust and can scar the landscape. This disused copper mine in Ajo, Arizona, measures one mile wide. Extracting metals causes huge amounts of waste. Copper production discards 99.5% of the extracted ore. Photo credit: NASA The image was taken by astronauts aboard the International Space Station and shows the New Cornelia Mine, just south of Ajo, Arizona. The disused pit measure one mile wide and over one thousand feet deep. Teacher notes More statistics about metal extraction are available at (American Association for the Advancement of Science) Harmful waste gases, including sulfur dioxide, carbon dioxide and carbon monoxide, are produced by extraction. Extraction, especially electrolysis, also uses lots of electricity.

21 New mining techniques can decrease the effects of metal extraction on the environment.
Leaching uses less electricity than traditional mining and does not produce waste gases. Copper ores are treated with and dissolved in dilute sulfuric acid, producing copper sulfate. Electrolysis is then used to extract the copper. Certain bacteria can also be used to dissolve ores and form copper sulfate. Phytomining uses plants to absorb metals from the soil. The process can be used to clean contaminated land. Treating the plants with certain chemicals increases their ability to accumulate minerals in their cells. Teacher notes More information about phytomining is available at:

22 Metals are easier to recycle than plastic and they retain their original properties, such as conductivity and hardness. Recycling uses up to 95% less electricity than producing metals from ores. Recycling costs less than extracting metals and can be profitable. Recycling creates less waste and reduces the number of sites that have to be mined. One problem is that metallic materials in recycled objects are often mixtures of different metals. This can mean that obtaining pure metals from recycling is more expensive, as it may use more electricity than extracting metals from ores.

23 Teacher notes This virtual experiment illustrates how copper can be purified using electrolysis. It could be used as a precursor to running the practical in the lab or as a revision exercise.

24 Electrolysis is a process that uses electricity to separate the elements in a compound. The word electrolysis means ‘splitting with electricity’. Electrolysis is expensive and so it is only used to extract reactive metals that cannot be extracted in other ways. Aluminium is a reactive metal that is found in the ore bauxite. It is combined with oxygen as aluminium oxide. Electrolysis is used to remove the oxygen and extract aluminium, which means that reduction takes place. What is the word equation for the extraction of aluminium? aluminium oxide aluminium oxygen +

25 Copper is not very reactive and can occur native but it is rare to
Copper is an excellent conductor and does not corrode quickly. These properties make it a good material for wiring and plumbing. Only pure copper can be used for electric wires. Even a very low level of impurities will reduce copper’s conductivity. Copper is not very reactive and can occur native but it is rare to find pure copper. Usually, it is found combined with other elements, such as in the ore malachite. Teacher notes Malachite is the mineral form of copper carbonate-hydroxide. It is mined for copper but also used as a decorative stone because of its attractive green appearance The copper extracted from compounds by reduction with carbon is impure. Electrolysis can actually be used at this stage to remove the impurities and obtain pure copper.

26 Teacher notes This drag and drop activity could be used as a plenary or revision exercise to check students’ ability to label the parts and reactants involved in the electrolysis of copper.

27 plenary A ……… furnace is used to reduce ………..
Impurities, iron ore (haematite), slag, coke, reduced, road, limestone, oxidised, slag A ……… furnace is used to reduce ……….. The solid raw materials are iron ore, ……….. and …………. Coke is first …………. to carbon monoxide, and this gas ………….. the iron ore. Limestone is added to remove the …………. and makes …………., which is used as ……. making material and breezeblocks.

28 By the end of the lesson I can:
Learning Objectives: By the end of the lesson I can: Explain where metals are obtained from. Give examples of how metals are extracted from the Earth. Metals that are less reactive than carbon can be extracted from their oxides by reduction in carbon, for example iron oxide is reduced in the blast furnace to make iron. Identify that metals less reactive than carbon can be extracted by reducing their oxides. Explain that iron is extracted in a blast furnace. •Consider and evaluate the social, economic and environmental impacts of exploiting metal ores, of using metals and of recycling metals. EXT: Explain how electrolysis works and why it is not always used


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