What is the Value of Avogadro's Number for Ru in hcp Packing?

[vipertongn]

Homework Statement

The element Ru has hcp packing with a hexagonal unit cell. The density of Ru is 12410 kg/m^3 and the cell volume is 2.711 x 10-23 mL. Calculate the value of Avogadro's number to three significant figures based on these data. (Note: the value may differ from the tabular value).

Homework Equations

D= 12410 kg/m^3 , V= 2.711 x 10-23 mL

The Attempt at a Solution

6 atoms (m^3/12410 kg)(1/2.711e-23 mL)(1000 mL/1 L)(1 L/0.001 m^3)(1 kg/1000g)(101.07 g/1 mol)

I end up with 1.80e24 which is 3x the true value...this method works for every other structure but the hcp

 

[Borek]

Are you sure it is six atoms per unit cell?

 

[vipertongn]

I was told that for the base its 2 for simple its 1 and for face its 4, but hcp no one told me except for a tutor and he said it was 6. Is it wrong?

 

[Borek]

http://www.chem.ox.ac.uk/icl/heyes/structure_of_solids/lecture1/Lec1.html