Copper crystal has a face -centred cubic lattice structure. Atomic radius of copper atom is 128 pm. Calculate the density of copper . Atomic mass of copper = 63.5 orCopper crystallises into a fcc lattice, its edge lengthis3.62 xx 10^(-8)cm. Calculate the dinsity of copper(atomic mass of Cu= 63.5 u,N_(A) = 6.022 xx 10^(23)"mol"^(-1))

Copper crystal has a face -centred cubic lattice structure. Atomic rad

1.	Copper crystal has a face -centred cubic lattice structure. Atomic radius of copper atom is 128 pm. Calculate the density of copper . Atomic mass of copper = 63.5 orCopper crystallises into a fcc lattice, its edge lengthis3.62 xx 10^(-8)cm. Calculate the dinsity of copper(atomic mass of Cu= 63.5 u,N_(A) = 6.022 xx 10^(23)"mol"^(-1))
Answer» Solution :For fcc , `r= a/sqrt2 or a = 2sqrt2r = 2xx 1.414 xx 128"pm"` = 362 pm `p = (Z xx M)/(a^(3) xx N_(0)) = ( 4xx 63.5 "g MOL"^(-1))/((362xx10^(-10)"cm")^(3) xx (6.02 xx 10^(23)"mol"^(-1)))= 8.9"cm"^(-3)` Alternatively, `p = ( "MASS of unit cell")/("volume of unit cell") = ( 4xx(63.5 "g mol"^(-1)//6.02xx10^(23)"mol"^(-1)))/((362xx 10^(-10)"cm")^(3))= 8.9 "g cm"^(-3)`