a fertiliser contains ammonium sulphate and potassium sulphate . when 0.5g of the fertliser was warmed up with sodium hydroxide solution , ammonia gas was evolved . the ammonia required 15cm^3 of 0.2M hydrochloric acid to neutralise it . what is the percentage by mass of ammonium sulphate in the fertiliser ?
- (NH4)2SO4 + 2NaOH-2NH3 + NA2SO4 + 2H20
- NH3 + HCL - NH4CL
- work out moles of HCl
- moles = 15 x 0.2/1000 = 0.003
- so moles of NH3 = 0.003 in equation 1
- moles of (NH4)2SO4 in equation 2 = 0.003/2 = 0.0015
- mass of (NH4)SO2 moles = mass/mr
- 0.0015 = x/132
- 0.0015 x 132 = x = 0.198 g
- percentage of ammonium sulphate =
- mass of ammonium sulphate
- -------------------------------- x 100
- mass of fertliser
- 0.198
- -------- x 100 = 39.6%
- 0.50