In the unit cell of sphalerite,Zn²⁺ ions occupy half the tetrahedral holes in a face-centered cubic lattice of S²^- ions.The number of formula units of ZnS in the unit cell is: A)6 B)4 C)3 D)2 E)1

Question

Quizplus · Accepted Answer

In face-centered cubic (fcc) lattice, there are 4 tetrahedral holes and 8 octahedral holes in the unit cell.

Each tetrahedral hole is shared by 4 adjacent unit cells. Therefore, the number of tetrahedral holes in the unit cell = 4 x 1/8 = 0.5

In sphalerite, ZnS ions (with 2 ions per formula unit) occupy half of the tetrahedral holes. Therefore, each unit cell contains 0.5 x 2 = 1 formula unit of ZnS.

Therefore, the number of formula units of ZnS in the unit cell = 1.

Hence, the answer is B) 4.

In the Unit Cell of Sphalerite,Zn2+ Ions Occupy Half the Tetrahedral

In the Unit Cell of Sphalerite,Zn²⁺ Ions Occupy Half the Tetrahedral