Balance the following redox reaction in acidic medium and determine the stoichiometric coefficient of $\text{H}_2\text{O}$ in the final balanced equation.
\[\text{MnO}_4^-(aq) + \text{Fe}^{2+}(aq) \rightarrow \text{Mn}^{2+}(aq) + \text{Fe}^{3+}(aq)\]