Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

$\text{Na}_2\text{S}_2\text{O}_3$ reacts with $\text{HCl}$ as shown. $\text{Na}_2\text{S}_2\text{O}_3\text{(aq)} + 2\text{HCl(aq)} \rightarrow 2\text{NaCl(aq)} + \text{H}_2\text{O(l)} + \text{SO}_2\text{(g)} + \text{S(s)}$ To determine the oxidation number of sulfur in $\text{Na}_2\text{S}_2\text{O}_3$, the mean oxidation number for the two sulfur atoms should be used. State the oxidation number of sulfur in each of $\text{Na}_2\text{S}_2\text{O}_3$, $\text{SO}_2$, and $\text{S}$?

  • A$+2$, $+2$, $+1$
  • B$+2$, $+4$, $0$
  • C$+4$, $+4$, $0$
  • D$+5$, $+4$, $0$

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