- #1
physicsnnewbie
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Homework Statement
Cobalt has an HCP (hexagonal close packed) crystal structure, an atomic radius of 0.1253 nm and a c/a ratio of 1.623. Compute the volume of the unit cell for cobalt.
Homework Equations
area of hexagon = apothem*perimeter/2
The Attempt at a Solution
calculate 1 of the 6 sides (2 atomic radii per side):
2*.1253 = 2.506e-1
calculate perimeter:
2.506e-1*6 = 1.5036e+0
calculate height:
2.506e-1*1.623 = 4.06724e-1
calculate hexagon area (apothem = 2 radii):
1.5036e+0*2.506e-1 / 2 = 1.88401e-1
calculate volume:
1.88401e-1*4.06724e-1 = 7.66272e-2
my answer:
7.66272e-2
correct answer:
6.64e-2 nm3