Electron Transfer Reactions · Paper 1 — Free Chemistry HL Practice Questions

In the blast furnace extraction of iron, iron(III) oxide is reduced to molten iron according to the equation: $$\text{Fe}_2\text{O}_3\text{(s)} + 3\text{CO(g)} \rightarrow 2\text{Fe(l)} + 3\text{CO}_2\text{(g)}$$ Which species undergoes oxidation in this reaction?

In a standard Daniell cell, a zinc electrode in $1.0\ \text{mol dm}^{-3}$ $\text{ZnSO}_4(\text{aq})$ and a copper electrode in $1.0\ \text{mol dm}^{-3}$ $\text{CuSO}_4(\text{aq})$ are connected by a salt bridge. The measured cell potential is $+1.10\ \text{V}$. Which statement correctly identifies the reducing agent and its role in this cell?

In a titration, $25.0 \ \text{cm}^3$ of $0.0200 \ \text{mol dm}^{-3}$ acidified $\text{KMnO}_4$ reacts exactly with $25.0 \ \text{cm}^3$ of $\text{FeSO}_4$ solution. The $\text{MnO}_4^-$ ion is reduced to $\text{Mn}^{2+}$ and $\text{Fe}^{2+}$ is oxidised to $\text{Fe}^{3+}$. What is the concentration, in $\text{mol dm}^{-3}$, of the $\text{FeSO}_4$ solution?

In a galvanic cell, a magnesium electrode in $1.0\ \text{mol dm}^{-3}\ \text{Mg(NO}_3)_2\text{(aq)}$ is connected by a salt bridge to a copper electrode in $1.0\ \text{mol dm}^{-3}\ \text{Cu(NO}_3)_2\text{(aq)}$. The standard electrode potentials are $E^\circ(\text{Mg}^{2+}/\text{Mg}) = -2.37\ \text{V}$ and $E^\circ(\text{Cu}^{2+}/\text{Cu}) = +0.34\ \text{V}$. Which row correctly identifies the direction of electron flow in the external circuit and the species oxidised?