Question

Fe2O3+H2O -> H2Fe2O4? или как?

Answer 1

Fe2O3+3H2O = 2Fe(OH)3
вроде, так

Answer 2

Almost, but not quite. The correct balanced chemical equation for the reaction between iron(III) oxide (Fe2O3) and water (H2O) is:

Fe2O3 + 3H2O -> 2Fe(OH)3

In this reaction, iron(III) oxide reacts with water to form iron(III) hydroxide.

The reaction you mentioned, H2Fe2O4, doesn't represent a valid chemical formula or compound. Iron(III) hydroxide (Fe(OH)3) is the correct product formed in this reaction.