Question

What is equivalent weight of H2O2 in decomposition reaction?

Answer 1

The equivalent weight of `"H"_2"O"_2` is 34.01 g.

Explanation:

The equivalent weight is the molecular weight (`"MM"`) divided by the number of electrons transferred per mole of reactant (`n`).

`color(blue)(bar(ul(|color(white)(a/a)"Equivalent weight" = "MM"/ncolor(white)(a/a)|)))" "`

We need the moles of electrons, so let's balance the equation by the ion-electron method.

Unbalanced equation: `"H"_2"O"_2 → "H"_2"O" + "O"_2`

Reduction: `1 × ["H"_2"O"_2 + "2H"^"+" + 2"e"^"-"→ "2H"_2"O" ]`
Oxidation: `1 × ul(["H"_2"O"_2 → "O"_2 + "2H"^"+" + "2e"^"-"]color(white)(mm))`
Overall: `color(white)(mmmm)2"H"_2"O"_2 → "O"_2 + "2H"_2"O"`

We see that the reaction involves the transfer of 2 mol of electrons.

Since the reaction also involves 2 mol of `"H"_2"O"_2`, the number of electrons transferred per mole of `"H"_2"O"_2` is

`n = ("2 mol e"^"-")/("2 mol H"_2"O"_2) = 1color(white)(l) "mol electrons per mole of H"_2"O"_2"`

∴ `"Equivalent weight" = "MM"/n = "34.01 g"/1 = "34.01 g"`

The equivalent weight of `"H"_2"O"_2` in this reaction is 34.01 g.