3 Substitution reactions

 

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Oxford Textbook Pages : 383 - 385

CGP Revision Guide Pages : 116

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Show Specification Ref : 3.2.5.2

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Question 1 / 5

AQA Jan 2010 Paper 5 Q7 this question is about some reactions of cobalt compounds areas outside the box will not be scanned for marking na co aq cocl aq pink solution concentrated nh aq concentrated hcl aq h o aq pale brown solution dark brown solution excess h nch ch nh a give the formula of the complex responsible for the pink colour in aqueous cocl and name its shape formula name of shape marks b give the formula of the cobalt containing compound v and describe its appearance formula appearance marks c write an equation for the reaction that occurs when the pink solution is converted into w marks wmp jan chem d give the formula of the cobalt containing complex in x and state the role of the h o in this reaction areas outside the box will not be scanned for marking formula role of h o marks e give the formula of the cobalt containing complex in y and explain why this complex is more stable than the cobalt containing complex in w formula explanation marks f identify the cobalt containing complex in solution z and explain why its co ordination number is different from that in the pink solution of cocl complex explanation marks turn over for the next question turn over wmp jan chem
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Question 2 / 5

AQA Jan 2012 Paper 5 Q7 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 3 / 5

AQA Jan 2012 Paper 5 Q8 do not write outside the box in its reactions with transition metal ions ammonia can act as a br nsted lowry base and as a lewis base a define the term lewis base mark b write an equation for a reaction between aqueous copper ii ions cu h o and ammonia in which ammonia acts as a br nsted lowry base state what you would observe marks extra space c write an equation for a different reaction between aqueous copper ii ions cu h o and ammonia in which ammonia acts as a lewis base but not as a br nsted lowry base state what you would observe marks extra space wmp jan chem do not write outside the box d an excess of dilute ammonia solution is added to an aqueous solution containing iron ii ions in a test tube that is then left to stand for some time state and explain what you would observe marks extra space e diaminoethane h nch ch nh like ammonia can react as a base and as a ligand e i write an equation for the reaction that occurs between an aqueous solution of aluminium chloride and an excess of aqueous diaminoethane describe the appearance of the aluminium containing reaction product marks extra space question continues on the next page turn over wmp jan chem do not write outside the box e ii write an equation for the reaction that occurs between an aqueous solution of cobalt ii sulfate and an excess of aqueous diaminoethane draw a diagram to show the shape of and bonding in the complex product write an equation for the reaction that would occur if the complex product of this reaction were allowed to stand in contact with oxygen gas marks end of questions wmp jan chem there are no questions printed on this page do not write on this page answer in the spaces provided wmp jan chem there are no questions printed on this page do not write on this page answer in the spaces provided copyright aqa and its licensors all rights reserved wmp jan chem
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Question 4 / 5

AQA Jun 2013 Paper 5 Q8 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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Question 5 / 5

AQA Jun 2016 Paper 5 Q8 section b answer all questions in the spaces provided do not write outside the box this question is about cobalt chemistry a give the electron configuration of the co atom and of the co ion state three characteristic features of the chemistry of cobalt and its compounds marks wmp jun chem do not write outside the box b ethane diamine can act as a bidentate ligand when co h o aq ions are treated with an excess of ethane diamine the water ligands are replaced explain what is meant by the term bidentate ligand explain with the aid of an equation the thermodynamic reasons why this reaction occurs draw a diagram to show the structure of the complex ion formed marks turn over wmp jun chem
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