The density of solid W is 19.3 g/cm3. How many atoms are present per cubic centimeter of W?

As a solid, W adopts a body-centered cubic unit cell. How many unit cells are present per cubic centimeter of W?

What is the volume of a unit cell of this metal?

What is the edge length of a unit cell of W?

Please explain! Thanks!

2 answers

In 1 cc of W you have 19.3 grams. There are 6.02E23 atoms in 183.84
# atoms 19.3 g = 19.3/6.02E23 = ?

The volume of a unit cell is v = mass/density.
mass unit cell = 2*183.84/6.02E23 = 6.2E-22 but you need to do that more accurately. (Note: The 2 comes from "there are two atoms per unit cell".)
Density = 19.3 from the problem.
volume = 3.2E-23 cc = volume unit cell.

edge length = V1/3
6.326