CIE Jun 2013 v1 Paper 2 Q1

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Examiners For Use Answer all the questions in the spaces provided. A sample of a fertiliser was known to contain ammonium sulfate, (NH4)2SO4, and sand only. A 2.96 g sample of the solid fertiliser was heated with 40.0 cm3 of NaOH(aq), an excess, and all of the ammonia produced was boiled away. After cooling, the remaining NaOH(aq) was exactly neutralised by 29.5 cm3 of 2.00 mol dm3 HCl. In a separate experiment, 40.0 cm3 of the original NaOH(aq) was exactly neutralised by 39.2 cm3 of the 2.00 mol dm3 HCl. (a) (i) Write balanced equations for the following reactions. NaOH with HCl(NH4)2SO4 with NaOH(ii) Calculate the amount, in moles, of NaOH present in the 40.0 cm3 of the original NaOH(aq) that was neutralised by 39.2 cm3 of 2.00 mol dm3 HCl. (iii) Calculate the amount, in moles, of NaOH present in the 40.0 cm3 of NaOH(aq) that remained after boiling the (NH4)2SO4. (iv) Use your answers to (ii) and (iii) to calculate the amount, in moles, of NaOH that reacted with the (NH4)2SO4.UCLES 2013 9701/21/M/J/13<br /> Examiners For Use (v) Use your answers to (i) and (iv) to calculate the amount, in moles, of (NH4)2SO4 that reacted with the NaOH. (vi) Hence calculate the mass of (NH4)2SO4 that reacted. (vii) Use your answer to (vi) to calculate the percentage, by mass, of (NH4)2SO4 present in the fertiliser. Write your answer to a suitable number of signi cantgures. [9] (b) The uncontrolled use of nitrogenous fertilisers can cause environmental damage to lakes and streams. This is known as eutrophication. What are the processes that occur when excessive amounts of nitrogenous fertilisers get into lakes and streams?[2] (c) Large quantities of ammonia are manufactured by the Haber process. Not all of this ammonia is used to make fertilisers. State one large-scale use for ammonia, other than in the production of nitrogenous fertilisers.[1] [Total: 12]UCLES 2013 9701/21/M/J/13 [Turn over<br />

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