6 Shape of complex ions

 

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Oxford Textbook Pages : 362 - 363

CGP Revision Guide Pages : 110, 113

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Show Specification Ref : 3.2.5.3

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Question 1 / 5

AQA Jan 2010 Paper 5 Q6 the complex cisplatin acts as an anticancer drug by changing the properties of dna when it reacts with guanine a component of dna areas outside the box will not be scanned for marking cl cl pt nh nh connects to dna chain cisplatin guanine when cisplatin is absorbed into the human body it undergoes a ligand substitution reaction and one chloride ligand is replaced by a water molecule forming a complex ion q a write an equation for this substitution reaction to form the complex ion q marks b the complex ion q can bond to guanine in two different ways b i the first way involves a hydrogen atom from one of the ammonia ligands on q bonding to an atom in a guanine molecule state the type of bond formed to guanine and identify an atom in guanine that could form a bond to this hydrogen atom type of bond atom in guanine marks b ii the second way involves a ligand substitution reaction in which an atom in a guanine molecule bonds to platinum by displacing the water molecule from q state the type of bond formed between guanine and platinum when a water molecule is displaced and identify an atom in guanine that could bond to platinum in this way type of bond atom in guanine marks wmp jan chem c state and explain one risk associated with the use of cisplatin as an anticancer drug risk explanation marks areas outside the box will not be scanned for marking turn over for the next question turn over wmp jan chem
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Question 2 / 5

AQA Jan 2011 Paper 5 Q4 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 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 2011 Paper 5 Q7 section b answer all questions in the spaces provided do not write outside the box this question is about copper chemistry a aqueous copper ii ions cu h o aq are blue a i with reference to electrons explain why aqueous copper ii ions are blue marks extra space a ii by reference to aqueous copper ii ions state the meaning of each of the three terms in the equation e hv marks extra space wmp jun chem do not write outside the box a iii write an equation for the reaction in aqueous solution between cu h o and an excess of chloride ions state the shape of the complex produced and explain why the shape differs from that of the cu h o ion marks extra space b draw the structure of the ethanedioate ion c o explain how this ion is able to act as a ligand marks question continues on the next page turn over wmp jun chem do not write outside the box c when a dilute aqueous solution containing ethanedioate ions is added to a solution containing aqueous copper ii ions a substitution reaction occurs in this reaction four water molecules are replaced and a new complex is formed c i write an ionic equation for the reaction give the co ordination number of the complex formed and name its shape marks c ii in the complex formed the two water molecules are opposite each other draw a diagram to show how the ethanedioate ions are bonded to a copper ion and give a value for one of the o cu o bond angles you are not required to show the water molecules marks wmp jun chem
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Question 5 / 5

AQA Jun 2014 Paper 5 Q7 section b answer all questions in the spaces provided do not write outside the box the characteristic properties of transition metals include coloured ions complex formation and catalytic activity a consider the chromium complexes p and q cr h o aq red violet cr h o cl aq green explain with reference to oxidation states and electron configurations why the chromium ions in complexes p and q contain the same number of d electrons you should not consider the electrons donated by the ligands explain in terms of electrons why the complexes are different colours you are not required to explain why the observed colours are red violet and green marks wmp jun chem do not write outside the box b write an equation to show how the co nh aq ion reacts with diaminoethane explain the thermodynamic reasons why this reaction occurs marks question continues on the next page turn over wmp jun chem do not write outside the box c the toxic complex cisplatin is an effective anti cancer drug because it reacts with the dna in cancer cells preventing cell division c i draw the displayed structure of cisplatin on your structure show the value of one of the bond angles at platinum state the charge if any on the complex marks c ii when cisplatin is ingested an initial reaction involves one of the chloride ligands being replaced by water write an equation for this reaction mark c iii suggest how the risk associated with the use of this drug can be minimised mark wmp jun chem do not write outside the box d explain with the aid of equations how and why vanadium v oxide is used in the contact process marks turn over for the next question turn over wmp jun chem
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