Question

Calcium metal crystallizes in a face -centred cubic lattice with edge of 0.556 nm. Calculate the density of the metal if it contains (i) 0.5 % Frenkel defects (ii) 0.2 % Schottky defects .

Answer 1

(i) Frenkel defects have no effect on the density because number of atoms per unit cell remains the same.
For FCC, Z = 4 , For Ca, M = ` 40 " g mol"^(-1)`
Also, a = 0.556 nm = ` 0.556 xx 10^(-7)` cm.
Density , ` p = (Z xx M)/(a^(3) xx N_(0)) = (( 3.992) ( 40 " g mol"^(-1)))/(( 0.556xx 10^(-7) cm)^(3) ( 6.022 xx 10^(23) "mol"^(-1))) = 1.5427 " g cm"^(-3)`