Question: in a crystalline solid of XY3 cubic closed packed arrangement for its element Y,,,, X occupies.... ? Answer: 33% OCTAHEDRAL VOIDS. 

how was this worked out? not the math necessarily,, but the voids occupied by X being OCTAHEDRAL and not TETRAHEDRAL. i don’t understand this part. i’d really appreciate it if someone could walk me through the logic here. thanks.

Asked by astutijoshi | 3rd Jun, 2019, 05:12: PM

Expert Answer:

XY3 has CCP arrangement for element Y.
atoms in one unit cell of CCP = 4
No. of atoms of X = 4/3
No. of octahedral voids = 4
So, % of octahedral voids filled 
equals space fraction numerator begin display style bevelled 4 over 3 end style over denominator 4 end fraction cross times 100

space equals space 33 percent sign
The number of octahedral voids present in lattice is the same as the number of  close- packed particles,
whereas, the number of tetrahedral voids is the twise of that number.
Therfore the total number of octahedral voids is 4 and tetrahedral voids is 8 per unit cell.

Answered by Varsha | 4th Jun, 2019, 11:21: AM

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