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Quiz – Redox reactions

Redox reactions, which involve the transfer of electrons between substances, are fundamental to understanding processes like combustion, respiration, and corrosion. Test your understanding of redox reactions with a quiz.

Your turn – redox reactions

For questions 1—10, determine the oxidation numbers for the elements indicated.

  1. \(\ce{F}\) in \(\ce{F}_{2}\)

\(0\)

  1. \(\ce{Ca}\) in \(\ce{Ca}^{2+}\)

\(+2\)

  1. \(\ce{S}\) in \(\ce{SO}_{3}\)

\(+6\)

  1. \(\ce{P}\) in \(\ce{PO}_{4}^{3-}\)

\(+5\)

  1. \(\ce{Cr}\) in \(\ce{Cr}_{2}\ce{O}_{3}\)

\(+3\)

  1. \(\ce{Al}\) in \(\ce{AlCl}_{4}^{-}\)

\(+3\)

  1. \(\ce{N}\) in \(\ce{NH}_{4}^{+}\)

\(-3\)

  1. \(\ce{Mn}\) in \(\ce{KMnO}_{4}\)

\(+7\)

  1. \(\ce{Fe}\) in \(\ce{Fe}_{2}\ce{O}_{3}\)

\(+3\)

  1. \(\ce{C}\) in \(\ce{CO}\)

\(+2\)

For questions 11–16, identify the oxidising agent, reducing agent, atom oxidised and atom reduced.

  1. \(\ce{FeO}+\ce{CO}\rightarrow\ce{Fe}+\ce{CO}_{2}\)

Oxidising agent: \(\ce{FeO}\)

Reducing agent: \(\ce{CO}\)

Atom oxidised: \(\ce{C}\) in \(\ce{CO}\)

Atom reduced: \(\ce{F}\) in \(\ce{FeO}\)

  1. \(3\ce{MnO}_{2}+4\ce{Al}\rightarrow2\ce{Al}_{2}\ce{O}_{3}+3\ce{Mn}\)

Oxidising agent: \(\ce{MnO2}\)

Reducing agent: \(\ce{Al}\)

Atom oxidised: \(\ce{Al}\)

Atom reduced: \(\ce{Mn}\) in \(\ce{MnO2}\)

  1. \(\ce{Zn}+\ce{CuCl}_{2}\rightarrow\ce{ZnCl}_{2}+\ce{Cu}\)

Oxidising agent: \(\ce{CuCl2}\)

Reducing agent: \(\ce{Zn}\)

Atom oxidised: \(\ce{Zn}\)

Atom reduced: \(\ce{Cu}\) in \(\ce{CuCl2}\)

  1. \(\ce{Cl}_{2}+2\ce{KI}\rightarrow2\ce{KCl}+\ce{I}_{2}\)

Oxidising agent: \(\ce{Cl2}\)

Reducing agent: \(\ce{KI}\)

Atom oxidised: \(\ce{I}\) in \(\ce{KI}\)

Atom reduced: \(\ce{Cl}\) in \(\ce{Cl2}\)

  1. \(2\ce{Mg}+\ce{CO}_{2}\rightarrow2\ce{MgO}+\ce{C}\)

Oxidising agent: \(\ce{CO2}\)

Reducing agent: \(\ce{Mg}\)

Atom oxidised: \(\ce{Mg}\)

Atom reduced: \(\ce{C}\) in \(\ce{CO2}\)

  1. \(\ce{C}_{6}\ce{H}_{12}\ce{O}_{6}+6\ce{O}_{2}\rightarrow6\ce{CO}_{2}+6\ce{H}_{2}\ce{O}\)

Oxidising agent: \(\ce{O2}\)

Reducing agent: \(\ce{C6H12O6}\)

Atom oxidised: \(\ce{C}\) in \(\ce{C6H12O6}\)

Atom reduced: \(\ce{O}\) in \(\ce{O2}\)

For questions 17–18, balance the redox reactions, including states.

  1. \(\ce{H}^{+}+\ce{Al}\rightarrow\ce{Al}^{3+}+\ce{H}_{2}\)

\(6\ce{H}^{+}(\textrm{aq})+2\ce{Al}(\textrm{s})\rightarrow3\ce{H}_{2}(\textrm{g})+2\ce{Al}^{3+}(\textrm{aq})\)
  1. \(\ce{Cr}_{2}\ce{O}_{7}^{2-}+\ce{Fe}^{2+}\rightarrow\ce{Cr}^{3+}+\ce{Fe}^{3+}\)

\(14\ce{H}^{+}(\textrm{aq})+\ce{Cr}_{2}\ce{O}_{7}^{2-}(\textrm{aq})+6\ce{Fe}^{2+}(\textrm{aq})\rightarrow2\ce{Cr}^{3+}(\textrm{aq})+7\ce{H}_{2}\ce{O}(\textrm{l})+6\ce{Fe}^{3+}(\textrm{aq})\)

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