Iron and vanadium both have the bcc crystal structure, and v forms a substitutional solid solution for all concentrations at room temperature. compute the unit cell edge length for a 39 wt% fe - 61 wt% v alloy. the room-temperature density and atomic weight of fe are 7.87 g/cm3 and 55.85 g/mol, the room-temperature density and atomic weight of v are 6.10 g/cm3 and 50.94 g/mol, respectively.