Chemistry 9701 · AS & A Level · 8.2

8.2 — practice question

The sulfite ions, $\mathrm{SO_3^{2-}}$, react individually with zinc and with manganese dioxide. $a$, $b$, $c$, $d$, $w$, $x$, $y$ and $z$ each represent whole numbers. $a\mathrm{SO_3^{2-}(aq)} + b\mathrm{H_2O(l)} + \mathrm{Zn(s)} \rightarrow \mathrm{Zn^{2+}(aq)} + c\mathrm{OH^{-}(aq)} + d\mathrm{S_2O_4^{2-}(aq)}$ $\mathrm{MnO_2(s)} + w\mathrm{SO_3^{2-}(aq)} + x\mathrm{H^{+}(aq)} \rightarrow \mathrm{Mn^{2+}(aq)} + y\mathrm{S_2O_6^{2-}(aq)} + z\mathrm{H_2O(l)}$ Which values are correct for $a$, $b$, $w$ and $x$?

  • A$a=1$, $b=2$, $w=2$, $x=4$
  • B$a=2$, $b=2$, $w=2$, $x=4$
  • C$a=1$, $b=2$, $w=4$, $x=2$
  • D$a=2$, $b=2$, $w=4$, $x=2$

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