CAIE A-Level Chemistry A2 24.2.7 Redox Equations Using the Relevant Questions

Practise reversing oxidation half-equations, balancing electron transfer and combining half-equations into overall ionic equations.

Exam points

identify which half-equation is oxidised and reverse it before combining the reduction and oxidation processes
scale half-equations so electrons cancel, then add and cancel common species while conserving atoms and charge
write the final balanced ionic equation with appropriate acidic or aqueous species and verify its feasibility

[Maximum number: 1]

Titanium is a transition element in Period 4. It is commonly found as $\mathrm{TiO}_{2}$ in minerals.

The $\mathrm{TiO}^{2+}$ ion forms when $\mathrm{TiO}_{2}$ reacts with an excess of sulfuric acid.
$\mathrm{TiO}^{2+}$ can be reduced by zinc metal in acidic conditions to form a purple solution containing $\mathrm{Ti}^{3+}(\mathrm{aq})$ .

Write an ionic equation for the reduction of $\mathrm{TiO}^{2+}$ by zinc metal in acidic conditions.

$2 \mathrm{TiO}^{2+}+4 \mathrm{H}^{+}+\mathrm{Zn} \rightarrow 2 \mathrm{Ti}^{3+}+2 \mathrm{H}_{2} \mathrm{O}+\mathrm{Zn}^{2+}$

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CAIE A-Level Chemistry A2 24.2.7 Redox Equations Using the Relevant Questions question 1