Ammonium sulfate reacts with $\text{NaOH}$ in a $1\!:\!2$ ratio. Finish and balance the equation for this reaction: $(\text{NH}_4)_2\text{SO}_4 + 2\text{NaOH} \rightarrow \ldots\text{NH}_3 + \ldots + \ldots$
Write a balanced equation for the reaction of $\text{NaOH}$ with $\text{HCl}$.
Calculate the amount, in moles, of $\text{HCl}$ present in $31.2\,\text{cm}^3$ of $1.00\,\text{mol dm}^{-3}$ $\text{HCl}$.
Calculate the amount, in moles, of $\text{NaOH}$ contained in $50.0\,\text{cm}^3$ of $2.00\,\text{mol dm}^{-3}$ $\text{NaOH}$.
Use your answers to (i), (ii) and (iii) to calculate the amount, in moles, of $\text{NaOH}$ consumed in the reaction with $(\text{NH}_4)_2\text{SO}_4$.
A $5.00\,\text{g}$ sample of fertiliser containing $(\text{NH}_4)_2\text{SO}_4$ was heated with $50.0\,\text{cm}^3$ (an excess) of $2.00\,\text{mol dm}^{-3}\;\text{NaOH}$. After all the ammonia had been expelled, the mixture was cooled. The leftover $\text{NaOH}$ was then titrated with $1.00\,\text{mol dm}^{-3}\;\text{HCl}$ and $31.2\,\text{cm}^3$ were needed for neutralisation.
Use your answer to (iv) and the equation in (a) to calculate the amount, in moles, of $(\text{NH}_4)_2\text{SO}_4$ that reacted with $\text{NaOH}$.
Use your answer to (v) to calculate the mass of $(\text{NH}_4)_2\text{SO}_4$ that reacted with $\text{NaOH}$.
Hence, calculate the percentage purity of the ammonium sulfate fertiliser.