In the half-reaction method, water is used to balance oxygen atoms. Why can't O 2- ions be used instead?
- physandchemteachLv 71 decade agoFavorite Answer
The reaction takes place in an aqueous solution. There are no O 2- ions present in the solution - the oxygen must come from the water molecules.
- Gervald FLv 71 decade ago
If oxides are soluble, like sodium oxide, then they always react to form the hydroxide, which is strongly alkaline:
Na2O + H2O ---> 2NaOH.
If the oxides are insoluble (as most are) they won't do anything at all.
Most redox reactions take place in acid solution, where the added H+ ions go to make water, and that is why you balance the equation with water on one side, and H+ ions on the other.
- MadScientistLv 41 decade ago
O2- ions don't exist in the quantity that water does in an aqueous solution. Usually oxygen is found in the form of OH-. It is very rarely a single atom ion (O2-)