Question

Cu metal crystallies in face centred cubic lattic with cell edge, a =361.6pm. What is the density of Cu crystal ? (Atomic mass of copper =63.5 amu, `N_(A)=6.023xx10^(23)`)

Answer 1

We know
`Z=(a^(3)xxrhoxxN_(A))/(M)`
`:. Rho=(ZM)/(a^(3)N_(A))`
Z=4 for fcc unit cell , `M =63.5 g mol^(-1)`
`a= 361.6xx10^(-10) cm, N_(A)=6.023xx10^(23)`
Putting these values in (i), we get
`rho=(4xx63.5)/((36.6xx10^(-10))^(3)xx6.023xx10^(23))=8.94 g cm ^(-3)`