The amount of NH4+ ions present as NH4NO3 in a sample of fertilizer is to be determined. Direct titration of NH4+ would not reveal an accurate result. Instead, NH4NO3 is reacted with Xs NaOH and this solution is then titrated with HCl in order to determine the amount of -OH required to neutralize all the NH4+ ions.

1.50 g of fertilizer is transferred carefully into a 100 mL volumetric flask and made up to the mark, using distilled water. Aliquots of 10 mL of this solution are then added to conical flasks that also contain 40 mL of 0.210 M NaOH.

These solutions are then titrated with a standard solution of 0.26 M HCl (average titre is 28.80 cm3).

Calculate the number of moles of NH4+ ions in the 100 mL volumetric flask and the % by mass NH4NO3 in the fertilizer