Question

52. The structure of a ternary salt consists of anions, X, arranged in a cubic close-packed array (as shown below) and cations A and B (the cations are not shown). Cation A occupies all of the octahedral holes in the lattice. What fraction of the tetrahedral holes must be occupied by cation, B, to give an emprical formula of ABX? A. All of them B. one-half C. one-fourth D. one-eighth

Answer 1

In » =) =) closed cubic packed (CCP) Stouctere. anion forms lattice effective eternic no (z) =4 No. of Octer he chcel voids cov) = 2 = 4 No. of tetraphedsed voids (Tu) = 22=2(4) = 8 anion x ferms ccp lettice so inca unit cell no. of x ceters = = 4 Cetion A occupies all of the unit cell ov, so in a - no. of A ceters =z= 4 so fer fermula ABX , no. of cation B should be fer, so B heas to occupy 4 tetrahedral voids B=z=4 - so fermula A4 Bu xu - ABX y so B has to occupy 4 tetrahed reel voids mears half of the texteel (8) so Answer would be [ (B) one-half] Any