Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

During the treatment of domestic water supplies, chlorine is introduced into the water to produce $\text{HClO}$. $\text{Cl}_2(\text{aq}) + \text{H}_2\text{O(l)} \rightarrow \text{H}^+(\text{aq}) + \text{Cl}^-(\text{aq}) + \text{HClO(aq)}$ The $\text{HClO}$ then reacts further, forming $\text{ClO}^-$ ions. $\text{HClO(aq)} + \text{H}_2\text{O(l)} \rightarrow \text{H}_3\text{O}^+(\text{aq}) + \text{ClO}^-(\text{aq})$ Both $\text{HClO}$ and $\text{ClO}^-$ destroy bacteria through oxidation. What is the overall change in oxidation number of chlorine when the $\text{ClO}^-$ ion is formed from aqueous chlorine?

  • A$-1$
  • B$0$
  • C$+1$
  • D$+2$

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