A student proposes the following two half-reactions for the oxidation of hydrogen…
CHEMISTRY · Multi-part · A Level · Chemistry · Oxidation, reduction and redox reactions · Oxidation, reduction and redox reactions
Problem
A student proposes the following two half-reactions for the oxidation of hydrogen peroxide by permanganate ion in acidic solution.
Half-reaction I: MnO4−+8H++3e−⟶Mn2++4H2O
Half-reaction II: H2O2⟶O2+2e−+2H+
The student claims that the two half-reactions can be added directly to obtain a balanced overall reaction.
Verify whether the student’s claim is valid by analyzing conservation of charge and electron equivalence.
(1) Part 1: (a) Calculate the total charge (in coulombs of elementary charge units) on each side of Half-reaction I. State whether the charges are equal.
(2) Part 2: (b) Calculate the total charge on each side of Half-reaction II. State whether the charges are equal.
(3) Part 3: (c) When the two half-reactions are combined as written, determine the total number of electrons lost and gained. Does the electron transfer balance? Explain.
(4) Part 4: (d) Propose the smallest integer factor by which one of the half-reactions must be multiplied so that electrons lost equal electrons gained. Write the resulting overall reaction and demonstrate that charge is conserved on the final equation.