Beatty 14.3 METALS (W3) 2023 Answers

1 Beatty Secondary School Science Department (Chemistry Unit) Chemistry 6092 Name: ___________________________________ ( ) Date: _______________ Class: 4E___ TOPIC: EXTRACTION OF METALS AND RECYCLING (WORKSHEET 3) Learning Objectives: (a) Describe the ease of obtaining metals from their ores by relating the elements to their positions in the reactivity series. (b) Describe and explain the essential reactions in the extraction of iron using haematite, limestone and coke in the blast furnace. (c) Describe metal ores as a finite resource and hence the need to recycle metals, e.g. recycling of iron. (d) Discuss the social, economic and environmental issues of recycling metals. Multiple-Choice Questions 1 Which metal can be extracted by heating its oxide with carbon? A calcium B magnesium C potassium D zinc ( D ) 2 The positions of four metals in the reactivity series is shown below. W X Y Z reactivity increases Which metals are most likely to be extracted by electrolysis and by heating their oxides with coke? extraction by electrolysis extraction by heating the oxide with coke A metal Z metal W B metal X metal Y C metal Y metal Z D metal W metal Z ( A ) 3 Which reaction produces most of the carbon monoxide used to extract iron in the blast furnace? A burning coke in air B reacting coke with carbon dioxide C reacting iron oxide with coke D decomposition of limestone ( B )

2 4 Which substance is added to the blast furnace to remove impurities from iron ore? A carbon B haematite C limestone D slag ( C ) 5 Some metals can be extracted by heating their oxides with hydrogen. Which metal is most easily extracted by this method? A calcium B copper C sodium D zinc ( B ) 6 Which substance does not have to be added to the blast furnace in the extraction of iron? A air B coke C limestone D sand ( D ) 7 Which is not a reason for recycling metals? A There are limited amounts of metals in the Earth’s crust. B Energy is needed to extract new metals from their ores. C Pollution of land from discarded metals is prevented. D Energy is used in recycling metals. ( D ) 8 Titanium metal can be extracted by the reaction below. TiCl4 + 4Na → Ti + 4NaCl What deduction can be made about titanium from this reaction? A Titanium is above sodium in the reactivity series. B Titanium can also be obtained by heating its oxide with coke. C Sodium is more reactive than titanium. D Titanium can also be extracted by heating TiCl4 with aluminium. ( C ) 9 In the manufacture of iron by the blast furnace, which are the main gases that escape from the top of the blast furnace? A carbon monoxide, carbon dioxide, hydrogen. B nitrogen, carbon dioxide, carbon monoxide C nitrogen, oxygen, steam D oxygen, carbon dioxide, sulfur dioxide ( B ) 10 Which statement about the production of iron from haematite is correct? A Coke is used to oxidise slag. B Limestone is used to produce oxygen for the coke to burn. C Molten iron floats on slag at the furnace base. D The haematite is reduced by carbon monoxide. ( D )

3 11 In the table below, the first substance is added to the Blast Furnace and the second substance is the main impurity in the iron formed. Which pair of substances is correct? substance added to the Blast Furnace main impurity in the iron formed A calcium oxide silica B limestone carbon C quicklime iron(II) oxide D slaked lime iron(III) oxide ( B ) Structured Questions 12 The diagram shows the blast furnace for the extraction of iron. (a) Add the four missing labels to the diagram. (b) Name one iron ore and give its chemical name. iron ore: haematite chemical name: iron(III) oxide (c) (i) Name substance Q. limestone (ii) Explain why Q is added to the blast furnace. Limestone is added to remove sand impurities / acidic impurities from the ore. hot air molten iron molten molten slag hot air

4 (d) The iron ore reacts with a gaseous reducing agent to produce molten iron. (i) Name the reducing agent. carbon monoxide (ii) Write the equation for the production of this reducing agent. C + CO2 → 2CO (e) Explain why the temperature of slag coming out of the tap hole is much lower than the expected 1530 °C. The slag is a mixture containing impurities that lower the melting point. (f) Suggest why the furnace would explode if the damp substances of the raw materials were added at the top of the furnace. Iron and carbon would reduce the steam (water that is heated at high temperature) to hydrogen. The hydrogen would react with the oxygen in air to release a large amount of energy, leading to explosion. 13 Explain why carbon can be used to obtain iron from iron oxide but not to obtain calcium from calcium oxide. Carbon is more reactive than iron, but less reactive than calcium in the reactivity series. As such, carbon is able to displace / reduce iron from iron oxide to form iron, but unable to displace / reduce calcium from calcium oxide. As such, calcium can only be obtained through electrolysis. 14 Iron is extracted from iron ore in the Blast Furnace. The equations A, B, C, D and E show some reactions that happen in the Blast Furnace. A C + O2 → CO2 B CO2 + C → 2CO C Fe2O3 + 3CO → 2Fe + 3CO2 D CaCO3 → CaO + CO2 E SiO2 + CaO → CaSiO3 Use the letters, A, B, C, D and E to answer the following questions. (a) Which equation shows combustion? A (b) Which equation shows thermal decomposition? D (c) Which equation shows a reaction between an acidic compound and a base? E

5 (d) Which equation shows the formation of a toxic gas? B (e) Two equation s show different elements in compounds being reduced. Give the letters for these two equations. B and C (f) Iron from the Blast Furnace is further processed to make steel. Some types of steel contain more carbon than others. How are the properties of high carbon steel different from those of low carbon steel? High carbon steel is stronger and harder than low carbon steel. High carbon steel is less malleable/more brittle than low carbon steel. 15 The table gives some information on four metals. magnesium Mg platinum Pt nickel Ni zinc Zn percentage abundance in the Earth’s crust 1.9 0.0001 0.008 0.007 approximate annual world production / millions of tonnes 0.3 0.001 1 500 main compound from which metal is extracted MgCl2 found as the element NiS ZnS metal approximate price / S$ per kg 7 40000 10 1.4 position in the Reactivity Series [also compared with aluminium, iron and copper] above aluminium below copper between zinc and copper between aluminium and iron percentage of metal which is recycled 15 >90 25 25 (a) Which metal is most abundant in the Earth’s crust. magnesium (b) Arrange the four metals in order of reactivity, placing the most reactive first. magnesium, zinc, nickel and platinum (c) Suggest, with a reason, the method used to extract (i) nickel, Metals that are below zinc in the reactivity series are extracted by reduction with carb on. Since nickel is between zinc and copper in the reactivity series, nickel can be extracted through reduction with carbon. (ii) magnesium. Metals that are above