Material science: Imperfections in solids

[15543]

Determine the number of vacancies per cm^3 needed for a BCC iron crystal to have a density of 7.87 g/cm^3. The lattice parameter of the iron is 2.866x10^-8 cm and the atomic weight of the iron is 55.847 g/mol. Given: Avogradro's number, N=6.022x10^23 atoms/mol

Help please? i have no idea how to solve this question :( I am gona have my first test for material science on wednesday!

 

[Astronuc]

How many atoms in a unit cell? How many unit cells in 1 cm³? What is the average mass of an iron atom?

What is the theoretical mass of a cm³ of Fe?

 

[15543]

theyre not given:( that is why I am having a hard time solving the question now sir