PLEASEf you can help me with #12 a,b,c i am so lost! i have other questions like
ID: 545788 • Letter: P
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PLEASEf you can help me with #12 a,b,c i am so lost! i have other questions like this but i can just get help and explination on all of 12 i can solve the rest!
he cesium chloride structure, CsCI CI- CsCl -Cs Ct CaC In the CsO structure, the larger Cs·ions occupy simple cubic lance posses while the smaller a ion occupies the center of each cubic unit cell. Notice the Cs' ions ARE NOT touching along the unit cell edge as one would have in a metaic SC unit cell. We assume the Cs" and CT ions are touching along the BODY DIAGONAL Using this description of the Coc unit cell, answer the follewing questions 10) Determine the coordination number for each ion: Cs 11) How many ions of each type are within one unit cel" a. CT L CT ' 12) The ioaic radias of Cr- is 151 pm and that of CT 167 pm. Use this information to determine the unit cell ede length of CsCl in pm and cm. a) Find the density of Ga.(sur) b)Find the packing efficiency of this unit cell. Note: Not all atoms are identical. ModifiedExplanation / Answer
12) Because the Cs ion is at the center and the Cl- ions form the lattice the oppositely charged ions are touching along the body diagonal
Thus 2(r+ + r-) = body diagonal = a (square root of 3 )
where a = unitcell edge length
Thus 2(181+167) = 1.732 xa
Thus unit cell edge length a = 401.85 pm
a) CsCl is bcc lattic ewhich has one Cs and one Cl-(1/8x8) ions. Thus the units os CsCL in one unit cell =1
we know density of unit cell = number of units in unit cell x molar mass / avogdro number x volume
= 1unit of CsCl x 168.36g/mol/ 6.022 x1023 x (401x10-10 cm)3
= 4.33 g/cm3
b) packing efficiency = volume occupies by spheres/ volume of cube
= [volume of C s+ + volume of Cl-] / volume of cube
= [4/3 x pi x (r+)3 + 4/3 x pi x (r-)3] / a3
= 4/3 x (22/7) x 10-30 [(181)3 + (167)3] / (401x10-10)3
= 0.6880
That is the packing efficiency percentage = 68.8%
I hope this should help you.
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