Define what is meant by relative formula mass.
Draw a dot-and-cross diagram for the ammonium ion, $\text{NH}_4^+$. Show only the outer-shell electrons. Use $\times$ to represent electrons from nitrogen. Use $\bullet$ to represent electrons from hydrogen.
Suggest the shape of an ammonium ion and predict the bond angle.
Explain the meaning of the term weak Brønsted-Lowry acid.
Write an equation to show how the ammonium ion behaves in water. Include state symbols.
Use the changes in oxidation numbers to balance the equation for the reaction that occurs. $\text{MnO}_4^- (aq) + \ldots \text{Fe}^{2+}(aq) + \ldots \text{H}^+(aq) \rightarrow \ldots \text{Mn}^{2+}(aq) + \ldots \text{Fe}^{3+}(aq) + \ldots \text{H}_2\text{O}(l)$
State the role of the $\text{Fe}^{2+}$ ions in this reaction. Explain your answer.
Calculate the amount, in moles, of manganate(VII) ions that reacted.
Calculate the amount, in moles, of $\text{Fe}^{2+}$ ions in the sample of the salt.
Calculate the relative formula mass of $(\text{NH}_4)_2\text{Fe}(\text{SO}_4)_2 \cdot x\text{H}_2\text{O$.
Calculate the value of $x$.