Edexcel IAL Chemistry 8.8 Classifying redox reactions

List the initial and final values for the relevant element or elements, then test whether any value changes and whether one starting species undergoes both changes.

Exam points

Classify redox by showing that at least one oxidation number increases and another decreases.
Distinguish disproportionation by checking whether one starting species undergoes both changes.

[Maximum number: 1]

Which reaction is not a redox reaction?

$4 \mathrm{KClO}_{3}(\mathrm{~s}) \rightarrow 3 \mathrm{KClO}_{4}(\mathrm{~s})+\mathrm{KCl}(\mathrm{s})$

$2 \mathrm{HCl}(\mathrm{aq})+\mathrm{Ba}(\mathrm{OH})_{2}(\mathrm{aq}) \rightarrow \mathrm{BaCl}_{2}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})$

Zn(s) $+\mathrm{CuSO}_{4}(\mathrm{aq}) \rightarrow \mathrm{ZnSO}_{4}(\mathrm{aq})+\mathrm{Cu}(\mathrm{s})$

$\mathrm{Cl}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{HCl}(\mathrm{aq})+\mathrm{HClO}(\mathrm{aq})$

4KClO3 → 3KClO4 + KCl

2HCl + Ba(OH)2 → BaCl2 + 2H2O

Zn + CuSO4 → ZnSO4 + Cu

Cl2 + H2O → HCl + HClO

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8.8—Oxidation number is a useful concept in terms of the classification of reactions as redox and as disproportionation question 1