(A) Use the result of Practice Example 12-9A, the molar mass of K, and the Avogadro constant to calculate the density of potassium.

(B) Use the result of Practice Example 12-9B, the molar mass of Al, and its density (2.6984 g cm^-3) to evaluate the Avogadro constant, N_A.

Example 12-9A

(A) Potassium crystallizes in the bcc structure. What is the length of the unit cell in this structure? Use the metallic radius of potassium given in Figure 9-11.

Figure 9-11

Example 12-9B

(B) Aluminum crystallizes in an fcc structure. Given that the atomic radius of Al is 143.1 pm, what is the volume of a unit cell?

Transcribed Image Text:

Li 155 59 Na 190 Na+ 102 K 235 138 Be 112 Be2+ 152 27 Mg 160 Mg2+ 72 K+ Ca²+ Sc³+ Ca Sc 197 162 100 Rb Sr 248 215 Rb Sr²+ 118 75 Ti 147 Tj ²+ 86 134 V²+ 79 V3+ 64 128 Cr²+ 73 Cr 3+ Mn2+ 126 Ma Fe 127 Fe²+ Co²+ 124 62 ● 83 61 Fe³+ 55 125 55 128 Cu 69 Cu+ O 73 Ag 144 115 75 Cd 151 Ag Cd²+ B 84 Zn Ga 134 140 65 77 Co 3+ Ni2+ Cu2+ Zn²+ Ga³+ Ge²+ 95 Al 143 A1³+ 54 62 с In 3+ 75 80 Si 114 Ge 144 In Sn 158 163 73 Sn2+ 93 N 71 N3 171 109 120 Sb 166 Sb³+ 76 64 0² 140 $² 184 104 100 Se 118 Se² 198 60 Te2 133 221 181 Br 117 Br Te 137 136 196 I 220