AQA Jun 2012 Paper 5 Q6

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do not write outside the box solid iron ii ethanedioate dihydrate fec o h o has a polymeric structure two repeating units in the polymer chain are shown fe fe each iron ion is also bonded to two water molecules these are not shown in the diagram a name the type of bond that is represented by the arrows mark b in terms of electrons explain how the water molecules not shown in the diagram form bonds to the iron marks c predict the value of the bond angle between the two bonds to iron that are formed by these two water molecules mark wmp jun chem do not write outside the box d iron ii ethanedioate dihydrate can be analysed by titration using potassium manganate vii in acidic solution in this reaction manganate vii ions oxidise iron ii ions and ethanedioate ions a g sample of impure fec o h o was dissolved in an excess of dilute sulfuric acid and made up to cm of solution cm of this solution decolourised cm of a mol dm solution of potassium manganate vii d i use the half equations given below to calculate the reacting ratio of moles of manganate vii ions to moles of iron ii ethanedioate mno h e mn h o co e fe fe e c o mark d ii calculate the percentage by mass of fec o h o in the original sample if you have been unable to answer part d i you may assume that three moles of manganate vii ions react with seven moles of iron ii ethanedioate this is not the correct ratio marks turn over wmp jun chem

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