Question

Copper crystallise in fcc with radius 127.8pm calculate density

Answer 1

we have formula

density = zm/a^3Na

where z= effective number of atom

m= mass

Na= avogadro constant=6.022*10^23

a= edge length

for an fcc

z=4

r=((√3)/4)a

so a = 4r/√3

a=4*127.8/1.732

a=2.3*127.8=293.9 pm

a=293.9 * 10 ^ -12 m

so substitute all the values in formula

and for mass check your question it must be given or else normally mass of copper is 63.1 gm and then solve it