# [Chem] Ions' States of Matter when not in solution

1. Oct 13, 2007

### dt_

1. The problem statement, all variables and given/known data

Hydrogen peroxide decomposes into water and oxygen gas with the help of a catalyst. write the molecular formula and the redox half reactions.

2. Relevant equations

(N/A)

3. The attempt at a solution

the molec. formula is of course

$$2 H_{2}O_{2} (l) \stackrel{catalyst}{\rightarrow} 2 H_{2}O (l) + O_{2} (g)$$

now for the reduction and oxidation half reactions:

reduction
$$O^{2-}_{2} + 2 e^{-} \rightarrow 2 O^{2-}$$

oxidation
$$O^{2-}_{2} \rightarrow O_{2} (g) + 2 e^{-}$$

My question is, what states should each of these ions in the half reactions be in? Normally (like for double displacement rxns) I know the ions are aqueous, but that's when both reactants are aqueous/in solution. Should the peroxide ion here, for instance, be liquid (because hydrogen peroxide is a liquid) or should it be aqueous?