I’m sorry, but it seems you have made a mistake in the chemical formula. H2Cr6O7 is not a valid chemical formula. Chemical formulae must follow the rules regarding the number of atoms and the balance between atoms.
For example, H2CrO4 is the formula for chromic acid, an actual existing chemical substance. In this formula, there are 2 hydrogen (H) atoms, 1 chromium (Cr) atom, and 4 oxygen (O) atoms. This is a strong acid often used in oxidation reactions.
Please check again the chemical formula you would like to study and provide your request again.