CIE Nov 2013 v2 Paper 4 Q1

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Examiners For Use Section A Answer all the questions in the spaces provided. (a) Gaseous ammonia reacts with gaseous hydrogen chloride to form solid ammonium chloride. NH3 + HClNH4Cl The bonding in ammonium chloride includes ionic, covalent and co-ordinate (dative covalent) bonds. Complete the following dot-and-cross diagram of the bonding in ammonium chloride. For each of the six atoms show all the electrons in its outer shell. Three electrons have already been included. Use the following code for your electrons.electrons from chlorine x electrons from hydrogen o electrons from nitrogenCl [3] (b) When a sample of dry ammonia is needed in the laboratory, the gas is passed through a tower containing lumps of solid calcium oxide, CaO. (i) Suggest why the usual drying agent for gases, concentrated H2SO4, is not used for ammonia.(ii) Write an equation for the reaction between CaO and H2O.(iii) Suggest why CaO rather than MgO is used to dry ammonia.[3]UCLES 2013 9701/42/O/N/13<br /> Examiners For Use (c) (i) Write an equation showing the thermal decomposition of calcium nitrate, Ca(NO3)2.(ii) State and explain how the thermal stabilities of the nitrates vary down Group II.[4] [Total: 10]UCLES 2013 9701/42/O/N/13 [Turn over<br /> BLANK PAGEUCLES 2013 9701/42/O/N/13<br />

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