AQA Jun 2011 Paper 2 Q4

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do not write outside the box metals are usually extracted from oxides some of these oxides occur naturally other oxides are made by roasting sulfide ores in air producing sulfur dioxide as a by product for the extraction of some metals the oxide needs to be converted into a chloride a the ore molybdenite contains molybdenum disulfide mos the first stage in the extraction of molybdenum is to roast the ore in air to form molybdenum oxide moo and sulfur dioxide a i write an equation for the first stage in this extraction mark a ii the release of sulfur dioxide into the atmosphere causes environmental problems and wastes a valuable resource identify one environmental problem and identify one use for the sulfur dioxide environmental problem use for sulfur dioxide marks a iii pure molybdenum is formed in the second stage by the reduction of moo using hydrogen write an equation for this reaction mark a iv state one risk in using hydrogen gas in metal extractions mark wmp jun chem do not write outside the box b calcium is an expensive metal it is extracted by the electrolysis of molten calcium chloride b i state why calcium chloride must be molten for electrolysis to occur mark b ii write an equation for the reaction that takes place at the negative electrode during this electrolysis mark b iii identify the major cost in this extraction of calcium mark turn over for the next question turn over wmp jun chem

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