CIE Jun 2016 v2 Paper 4 Q1

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Answer all questions in the spaces provided. PMT (a) Magnesium nitrate, Mg(NO3)2, is very soluble in water. When a hot saturated solution of magnesium nitrate is cooled, crystals of the hydrate, Mg(NO3)2.6H2O, are formed. In the crystals, six water molecules bond to each Mg2+ ion, and some of these water molecules are also bonded to the nitrate ions. (i) Suggest the type of bonding that occurs between H2O and Mg2+,H2O and NO3 .[2] (ii) Describe the arrangement of the water molecules around the Mg2+ ion.[1] (iii) Describe in detail what you would observe when crystals of Mg(NO3)2.6H2O are heated in a boiling tube, gently at first and then more strongly. Write equations for any reactions that occur.[4] (iv) Calculate the percentage loss in mass when Mg(NO3)2.6H2O is heated strongly to constant mass.UCLES 2016 9701/42/M/J/16 percentage loss =% [2]<br /> PMT (b) Explain why the Group 2 nitrates become more stable to heat down the group.[2] (c) Magnesium nitrate and silver nitrate, AgNO3, decompose on heating to produce the same gases. Silver nitrate also produces silver metal during decomposition. Write an equation for the decomposition of AgNO3.[1] [Total: 12]UCLES 2016 9701/42/M/J/16 [Turn over<br />

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