Farmers use chemicals to improve crop yield. Ammonium phosphate, (NH4)3PO4, is used as a fertiliser and calcium hydroxide, Ca(OH)2, is used to reduce the acidity of soils. The relative formula mass of ammonium phosphate is 149.

1. (a)Calculate the percentage by mass of nitrogen in ammonium phosphate. percentage = % [1][1]
2. (b)(i)A farmer adds ammonium phosphate to a field. He then adds calcium hydroxide to the field because the soil is very acidic. Calcium hydroxide neutralises the acid in the soil. Give the ionic equation for this reaction. .[1][1]
3. (b)(ii)The calcium hydroxide reduces the effectiveness of the ammonium phosphate fertiliser because it reduces the nitrogen content. Explain why adding calcium hydroxide reduces the nitrogen content. ..[2][2]
4. (c)(i)A sample of ammonium phosphate can be produced by the reaction of aqueous ammonia and phosphoric acid. 3NH3(aq) + H3PO4(aq) → (NH4)3PO4(aq) 25.0 cm³ of 1.25 mol/dm³ phosphoric acid is neutralised by 45.3cm³ of aqueous ammonia. Calculate the concentration, in mol/dm³, of the ammonia used. concentration of ammonia = mol/dm³ [3][3]
5. (c)(ii)Show, by calculation, that 4.66g of ammonium phosphate would be produced. Assume that the yield is 100%. [Mr: (NH4)3PO4, 149] [1][1]
6. (c)(iii)In practice, the actual mass of ammonium phosphate produced is 2.93g. Calculate the percentage yield of ammonium phosphate. percentage yield = % [1][1]