1 General properties

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Oxford Textbook Pages : 400 - 404

CGP Revision Guide Pages : 164 - 167

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Show Specification Ref : 5.3.1a, 5.3.1b, 5.3.1c

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Question 1 / 5

June 2014 QP – Unit 2 AQA Chemistry A-level_question_3 do not write outside the box a antimony is a solid element that is used in industry the method used for the extraction of antimony depends on the grade of the ore antimony can be extracted by reacting scrap iron with low grade ores that contain antimony sulfide sb s a i write an equation for the reaction of iron with antimony sulfide to form antimony and iron ii sulfide mark a ii write a half equation to show what happens to the iron atoms in this reaction mark b in the first stage of the extraction of antimony from a high grade ore antimony sulfide is roasted in air to convert it into antimony iii oxide sb o and sulfur dioxide b i write an equation for this reaction mark b ii identify one substance that is manufactured directly from the sulfur dioxide formed in this reaction mark wmp jun chem do not write outside the box c in the second stage of the extraction of antimony from a high grade ore antimony iii oxide is reacted with carbon monoxide at high temperature c i use the standard enthalpies of formation in table and the equation given below table to calculate a value for the standard enthalpy change for this reaction table sb o s co g hf kj mol sb i co g sb o s co g sb i co g marks c ii suggest why the value for the standard enthalpy of formation of liquid antimony given in table is not zero mark c iii state the type of reaction that antimony iii oxide has undergone in this reaction mark d deduce one reason why the method of extraction of antimony from a low grade ore described in part a is a low cost process do not include the cost of the ore mark turn over wmp jun chem
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Question 2 / 5

June 2016 QP – Unit 2 AQA Chemistry A-level_question_7 do not write outside the box a the ores used for the extraction of many metals contain metal sulfides or metal oxides various methods are used to extract metals from these ores sulfide ores such as zinc blende zns are crushed and then roasted in a stream of air to convert them into the metal oxide a i write an equation for the reaction that takes place when zns is roasted in air mark a ii state a useful substance that can be manufactured from the gaseous product of this reaction mark b zinc oxide is reduced by carbon monoxide in the extraction of zinc the carbon monoxide is produced by the incomplete combustion of methane b i write an equation for the production of carbon monoxide by the incomplete combustion of methane mark b ii write an equation for the reaction between zinc oxide and carbon monoxide mark c most copper is produced by reduction of copper ii oxide with carbon the copper ii oxide is produced by roasting chalcopyrite cufes in air copper can also be obtained from other low grade ores when these low grade ores are processed aqueous solutions containing low concentrations of cu ions are produced scrap iron is used to recover copper from these solutions c i give the ionic equation for the reaction involved in the recovery of solid copper from an aqueous solution using scrap iron include state symbols mark turn over wmp jun chem do not write outside the box c ii suggest two environmental reasons and one economic reason why the extraction of copper from solutions containing cu ions using iron is preferable to the reduction of copper ii oxide made by roasting chalcopyrite marks environmental reason environmental reason economic reason d titanium can be extracted from its ore rutile tio in a two step process using carbon chlorine and magnesium extraction of titanium is not possible by direct reduction of tio with carbon d i give equations for the two step process using carbon chlorine and magnesium marks step step d ii state why direct reduction of tio with carbon cannot be used mark wmp jun chem do not write outside the box turn over for the next question do not write on this page answer in the spaces provided turn over wmp jun chem
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Question 3 / 5

January 2011 QP – Unit 5 AQA Chemistry A-level_question_4 do not write outside the box three characteristic properties of transition metals are complex formation coloured ions and catalytic activity a state the feature of transition metals that gives rise to these characteristic properties mark b state a fourth characteristic property of transition metals mark c for each of the following shapes of complex identify an appropriate example by drawing its structure c i a linear complex c ii a square planar complex c iii a tetrahedral complex question continues on the next page mark mark mark turn over wmp jan chem do not write outside the box d the chemical industry makes use of the catalytic activity of transition metal compounds for example vanadium v oxide is used as a heterogeneous catalyst in the contact process d i write an equation for the overall reaction in the contact process mark d ii explain the meaning of the term heterogeneous as applied to a catalyst mark d iii write two equations to illustrate how vanadium v oxide acts as a catalyst in the contact process equation equation marks d iv suggest what is done to a heterogeneous catalyst such as vanadium v oxide to maximise its efficiency and how this is achieved marks wmp jan chem do not write outside the box e the porphyrin ring is a multidentate ligand that is found in living systems complexed with iron ii ions in haemoglobin and with cobalt ii ions in vitamin b e i give the meaning of the term multidentate mark e ii a porphyrin ring can be represented by the symbol pr it reacts with aqueous iron ii ions as shown in the equation below the enthalpy change for this reaction is approximately zero pr aq fe h o aq fepr h o aq h o i explain why the free energy change for this reaction is negative marks e iii in vitamin b the cobalt ii ion is co ordinated to a porphyrin ring a cyanide cn ion and an additional unidentate ligand the cyanide ion is very toxic predict the co ordination number of the cobalt ion in vitamin b suggest why vitamin b is not toxic co ordination number reason why vitamin b is not toxic marks turn over wmp jan chem
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Question 4 / 5

January 2012 QP – Unit 5 AQA Chemistry A-level_question_7 section b answer all questions in the spaces provided do not write outside the box a due to their electron arrangements transition metals have characteristic properties including catalytic action and the formation of complexes with different shapes give two other characteristic properties of transition metals for each property illustrate your answer with a transition metal of your choice marks b other than octahedral there are several different shapes shown by transition metal complexes name three of these shapes and for each one give the formula of a complex with that shape marks wmp jan chem do not write outside the box c it is possible for group metal ions to form complexes for example the ca h o ion in hard water reacts with edta ions to form a complex ion in a similar manner to hydrated transition metal ions this reaction can be used in a titration to measure the concentration of calcium ions in hard water c i write an equation for the equilibrium that is established when hydrated calcium ions react with edta ions mark c ii explain why the equilibrium in part c i is displaced almost completely to the right to form the edta complex marks c iii in a titration cm of a mol dm solution of edta reacted completely with the calcium ions in a cm sample of a saturated solution of calcium hydroxide calculate the mass of calcium hydroxide that was dissolved in dm of the calcium hydroxide solution marks extra space turn over wmp jan chem
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Question 5 / 5

June 2013 QP – Unit 5 AQA Chemistry A-level_question_8 do not write outside the box this question explores some reactions and some uses of cobalt compounds a ethanal is oxidised to ethanoic acid by oxygen the equation for this reaction is ch cho o ch cooh this redox reaction is slow at room temperature but speeds up in the presence of cobalt compounds explain why a cobalt compound is able to act as a catalyst for this process illustrate your explanation with two equations to suggest how in the presence of water and hydrogen ions co and then co ions could be involved in catalysing this reaction marks wmp jun chem do not write outside the box b in aqueous solution the co h o ion reacts with an excess of ethane diamine to form the complex ion y b i write an equation for this reaction explain in terms of the chelate effect why the complex ion y is formed in preference to the co h o complex ion marks b ii draw a diagram that shows the shape of the complex ion y and shows the type of bond between the ethane diamine molecules and the cobalt question continues on the next page marks turn over wmp jun chem do not write outside the box c compound z is a complex that contains only cobalt nitrogen hydrogen and chlorine a solid sample of z was prepared by reaction of cm of mol dm aqueous cobalt ii chloride with ammonia and an oxidising agent followed by hydrochloric acid when this sample of z was reacted with an excess of silver nitrate g of silver chloride were obtained use this information to calculate the mole ratio of chloride ions to cobalt ions in z give the formula of the complex cobalt compound z that you would expect to be formed in the preparation described above suggest one reason why the mole ratio of chloride ions to cobalt ions that you have calculated is different from the expected value marks end of questions copyright aqa and its licensors all rights reserved wmp jun chem
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