Chemistry UNIT 6B question summer 2002 Watch
This question concerns methods for the determination of the ammonium and sulphate ions.
(a) A sample weighing 3.80 g was dissolved in water and the volume made to 250 cm3. To
25.0 cm3 portions of this solution about 5 cm3 (an excess) of aqueous methanal was
added. The following reaction took place:
4NH4+ (aq) + 6HCHO(aq)-----> C6H12N4(aq) + 4H+(aq) + 6H2O(l)
The liberated acid was titrated directly with 0.100 mol dm–3 aqueous sodium hydroxide.
The average volume required was 28.0 cm3. Calculate the percentage of ammonium
sulphate in the fertiliser.