KS4: Useful Materials From Metal Ores

1. KS4: Useful Materials FromMetal Ores

3. Getting metals from ores

4. Extraction of metals and energy changes 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.

5. Extraction processes

6. Extracting methods Here is a list of the symbols of some metals in order of decreasing reactivity- Li, Ce, Mn, Al, Zn, Cd, Sn, Pb, Cu, Pd Use this to assign the most likely method of extraction: native (N), carbon(C), electrolysis (E).

7. Extracting Gold Because gold occurs native its extraction is a low-tech affair that simply involves finding it!

8. Iron Iron is a moderately reactive metal. Iron ore is plentiful and relatively easily reduced to iron metal by heating with coal (carbon). It is therefore cheap. It is strong and malleable (non-brittle). Iron is the most commonly used metal.

10. Reactions - Reduction of iron ore

11. Reactions – Removing impurities

12. Extraction of Iron A drag and drop activity A drag and drop activity

13. Copper Copper is a metal of low reactivity. It occasionally occurs native but more often occurs as copper compounds. Heating copper compounds with carbon gives copper but this is not pure enough to use for electrical work.

14. Electrolytic purification The conductivity of copper is drastically reduced by tiny amounts of impurities. Because of this most copper metal is further purified by electrolysis. In this process impure anodes dissolve. This dissolved copper is plated onto a cathode leaving behind impurities.

15. Copper atoms at the cathode Opposite charges attract. Positive copper ions (Cu2+) move to the negative cathode. At the cathode these ions gain electrons and turn into copper atoms. So, during electrolysis a copper cathode gets thicker.

16. Copper ions form at the anode Impure copper is used as the anode of an electrolysis cell. The battery pulls electrons off the copper atoms in the anode. By losing electrons these atoms become copper ions and so the anode slowly ‘dissolves’ away. Impurities just sink to the bottom as ‘anode mud’.

17. Purification: The whole process

18. Purification: The half reactions

19. Copper is purified to improve its NOT CIVIC DUTY Copper is purified by CELERY IS LOST Pure copper forms at the DO TEACH Impurities form called A ODD MENU The anode will slowly DIVE LOSS At the cathode copper ions gain CORN STEEL

20. Extracting platinum Platinum is a rare and expensive metal used in jewellery and also for plating the fuel nozzles in jet engines. It was first discovered by Europeans in 1735 but in South America the primitive pre-Columbian Indians had been using it for centuries.

21. Purifying copper and electricity Copper is purified using electrolysis. Plan an experiment to investigate factors that might affect the rate of copper production. Include: Any factors that might affect rate. The apparatus you would need. A statement of how you would control variable in an investigation. The number and range of readings. The safety issues you would take into account.

22. Purifying copper: some answers (1) Some factors that might affect rate - Concentration of solution. Distance apart of electrodes Electrical potential (volts) or current (amps). Duration of electrolysis.

23. Control of variables Basically only change one variable at a time! Number and range of readings Minimum of 8-10 different values Repeat readings at least once Attempt a range providing 10-fold change Safety Issues Check electrical, toxicity, corrosive, etc. Take appropriate measures Purifying copper: some answers (2)

24. Aluminium: properties Aluminium is a reactive metal. We might expect it to corrode easily but a strong coating of oxide on it’s surface prevents this in most everyday situations. It has a low density which leads to its extensive use in the aerospace industry.

25. Aluminium: ores It occurs as bauxite ore which is a form of aluminium oxide. Because aluminium is so reactive carbon is unable to pull away the oxygen from it. It is extracted by electrolysis of molten bauxite. Early attempts at this failed because bauxite is so hard to melt. If cryolite is added, the bauxite melts more easily. This is an essential step in the extraction process.

27. Aluminium formation Opposite charges attract. And so positive aluminium ions move towards the negative cathode. At the cathode these ions gain electrons and turn into aluminium atoms.

28. Oxygen formation Negatively charged oxide ions move to the anode. Here they lose 2 electrons and so turn into neutral oxygen atoms. These atoms rapidly join into pairs to form normal oxygen gas.

29. Carbon dioxide formation Remember the electrolysis is carried out at high temperature. Under these conditions quite a lot of the oxygen reacts with the carbon anode. Carbon dioxide is formed and the anode is rapidly eaten away and frequently has to be replaced.

32. Common aluminium ore I axe tub Added to reduce melting point City role The electrodes are made out of Right ape Extracting aluminium is a Cretin duo

33. Aluminium – the overall process

34. A Rotten Week in the State of Chemark Since the war of 2042 world trade had been drastically reduced. Many countries have a policy of using home produced materials wherever possible because imported materials remain difficult to buy.

35. Chemsville The major town of Chemsville, in the state of Chemark, has 2 main industries: -ChemCars – manufacturing expensive cars -ChemComm – engaged in communications products such as newspapers, books, CDs and DVDs It also had an 80% completed aircraft factory: ChemJet -ChemJet has orders for 22 executive jets which they are committed to delivering to a tight schedule. There are also several large farms within the borders of Chemsville producing crops and meat.

36. Chemsville

37. Monday – Fire at ElectroSalt 1 The week starts badly! The company that electrolyses salt in Chemark has had a major fire. The ElectroSalt factory will not open again for at least 3 months. The mayor of Chemsville phones. She urgently wants you to produce a brief report setting out: What rock salt is used for? How the factory close-down may affect companies, farmers and non-industrial activities in Chemsville

38. Monday: Useful products from rocksalt

39. Monday: answers about rocksalt

40. Monday: answers about rocksalt

41. Monday: Useful products from rocksalt

42. Wednesday: Price Rises by ElectroGen ElectroSalt had been one of the major customers of the only Electricity company. Loss of ElectroSalt’s custom has taken ElectroGen into financial problems and they announce an emergency price rise of 50% for electricity. The mayor phones. What effect will this have upon the cost of products made in Chemsville?

43. Wednesday: Report about ElectroGen Obviously there are normal running costs in all of the organisations but two vital products will be hit by the price rise and are difficult to get replace. Copper – for wiring of cars and aircraft. (Copper is refined by electrolysis which uses large amounts of electrical power.) Aluminium – for use in cars and especially in aircraft. (Aluminium is extracted by electrolysis of molten bauxite.)

44. Friday: Limestone shortage It seemed things could only get better - wrong! The director of the unfinished aircraft factory phones saying the company providing cement has been unable to get supplies because of a strike at the limestone quarry. The aircraft factory must be finished on time. The director suggests using an old limestone wall and clay from the foundations of the new factory to make enough cement to finish the factory off. Is this feasible / sensible?

45. The limestone wall could be heated to produce calcium oxide and this could be mixed with clay to make cement so this could solve the problem. It might make more sense to ship the limestone to the existing cement factory to make a batch of cement as they already have the necessary equipment. This is my recommendation. Friday: Answers to limestone shortage

46. The building of the ChemJet factory is not the only thing that will be affected by a limestone shortage. The strike will affect manufacture of iron from which steel is made. This could have major effects on ChemCar as many car components are made of steel. In the longer term it will also affect farmers who use limestone to neutralise their soil. Friday: Answers to limestone shortage

47. Which of the following metals is most likely to occur native? Sodium Zinc Iron Gold

48. Which of the following metals has to be extracted by electrolysis? Sodium Zinc Iron Gold

49. Which of these happens in the purification of copper? Copper cathode dissolves Copper anode gets thicker Copper atoms become ions at the cathode Copper ions become atoms by gaining electrons.

50. Which of these happens in the extraction of iron? Carbon oxidises the iron oxide Combustion of carbon provides the energy for the extraction process. Carbon monoxide reacts with acidic impurities in the iron ore. The waste gas is mainly carbon monoxide