In crystalline solid anions ‘C’ are arranged in cubic close packing, cations ‘A’ occupy 50% of tetrahedral voids and cations ‘B’ occupy 50% of octahedral voids. What is the formula of the solid?
Let us assume that the number of atoms of element C = 4 (because CCP is present) ‘A’ occupy the 50% of tetrahedral void, so the number of A atoms in the element will be = 2 × 50100 × 4 = 42 × 50100 × 4 = 4 ‘B’ occupy the 50% of octahedral voids, so the number of B atoms in the element will be = 50/100 × 4 = 2 So, the ratio will be = A : B : C = 4 : 2 : 4 = 2 : 1 : 2 Therefore, the formula will be A2BC2
