Question

Which of the following represents a redox reaction?

Options

• \[\ce{NaOH + HCl -> NaCl + H2O}\]

• \[\ce{BaCl2 + H2SO4 -> BaSO4 + 2HCl}\]

• \[\ce{CuSO4 + 2H2O -> Cu(OH)2 + H}\]

• \[\ce{Zn + 2HCl -> ZnCl2 + H2}\]

Answer 1

\[\ce{Zn + 2HCl -> ZnCl2 + H2}\]

Explanation:

\[\ce{NaOH + HCl -> NaCl + H2O}\]

\[\ce{BaCl2 + H2SO4 -> BaSO4 + 2HCl}\]

In both above reactions is neutralisation.

Cu's oxidation state is +2 in both reactant and product and the \[\ce{SO^{2-}_4}\] ion remains unchanged.

So, \[\ce{Zn + 2HCl -> ZnCl2 + H2}\] is a redox reaction.

\[\ce{Zn -> Zn^{2+} + 2e^-}\] (Oxidation)

\[\ce{2H^+ + 2e^- -> H2}\] (Reduction)