Frequently Asked Question

Here is a possible explanation from a chemistry standpoint:

Oxalic acid does indeed require specific pH conditions for proper dissociation into oxalate ions. Oxalic acid is a weak acid with a pKa of approximately 1.27. This means that at pH values below 1.27, oxalic acid will predominantly exist in its undissociated form, while at pH values above 1.27, it will predominantly exist as oxalate ions.

In the reaction between oxalic acid and ferric oxide, hydrogen peroxide can act as a catalyst by providing an alternative pathway for the reaction to occur. In the absence of hydrogen peroxide, the reaction between oxalic acid and ferric oxide is slow and requires high temperatures. However, in the presence of hydrogen peroxide, the reaction can occur at much lower temperatures and at a much faster rate.

The mechanism for the catalytic effect of hydrogen peroxide is not fully understood, but it is thought to involve the formation of free radicals. Free radicals are highly reactive species that can initiate and propagate chain reactions, which can lead to a significant increase in the reaction rate.

Here is a simplified representation of the catalytic cycle involving hydrogen peroxide:

1. Hydrogen peroxide reacts with ferric oxide to form hydroxyl radicals and ferric ions:

H2O2 + Fe2O3 → 2 OH- + 2 Fe3+

2. Hydroxyl radicals react with oxalic acid to form carbon dioxide and water:

OH- + H2C2O4 → CO2 + H2O

3. Ferric ions react with oxalate ions to form ferric oxalate:

Fe3+ + 3 C2O42- → Fe2(C2O4)3

The overall reaction can be represented as:

H2C2O4 + Fe2O3 → CO2 + H2O + Fe2(C2O4)3

In this catalytic cycle, hydrogen peroxide is consumed in the first step but is regenerated in the third step. This allows hydrogen peroxide to act as a catalyst, even though it is not consumed in the overall reaction.