The amount of iron in ore can be quantitatively found by titrating a solution of the unknown with a standard solution of dichromate, Cr2O72? The net ionic equation is
6Fe2+(aq)+Cr2O72?(aq)+14H+(aq) 6Fe3+(aq)+2Cr3+(aq)+7H2O(aq)
The titration of 25.0mL of an iron (II) solution required 18.0mL of a 0.215M solution of dichromate to reach the equivalence point. Explain what is the molarity of the iron (II) solution?