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ID: 227966 • Letter: M

Question

me File Edit View History Bookmarks People Window Help n Grades: View Given That A Solid Crystallize. C www.webassign.net/web/Student/Assignment-Responses/submit?dep=1 76283 05#Q2 CH 102-Google Drive xPreview of Lab 6 PostLab 2/5 points | Previous packing efficiency, defined Given that a solid crystallizes in a body centered cubic structure that is 2.79 A on each side, answer questions (o)-(e). (1 A 1. x 10-10 m.) nChem102Labv1 6.POST.02. 1/3 Submissions Used In modeling solid-state structures, atoms and ions are most often modeled as spheres. A structure built using spheres will have some empty, or as the volume occupied by the spheres divided by the total volume of the structure. bic structure that is 2.79 A on each side, answer questions ()-(e). (1 A (a) How many total atoms are there in each unit cell? too high atom(s) (b) What is the volume of one unit cell in A3 10-10 m.) 21.7 A3 (c) Asuming that the atoms are spheres and the radius of each sphere is 1.21 A, what is 7.42 A3 the volume of one atom in A3 (Vsphere 4/3 (d) Therefore, what volume of atoms are in one unit cell? 29.6 A3 (e) Based on your results from parts (b) and (d), what is the packing efficiency of the solid expressed as a percentage 73.2 % Additional Materialts Solid State Modeling

Explanation / Answer

BCC unit cell

a) total atoms = 2

b) volume of unitc cell = A^3

      = 2.79^3

      = 21.7 angstrom^3

c) volume of an atom = 4/3*Pi*r^3

                     = (4/3)*3.14*(1.21)^3

                     = 7.42 A^3

d) volume of atoms = 2*7.42 = 14.84 A^3

e) packing efficiency = 14.84/21.7*100

           = 68.4%