Homework 4 - solutions

# Homework 4 - solutions - MAT 33 Fall 2008 Due: 09/22/08...

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MAT 33 – Fall 2008 Homework #4 - Solutions Due: 09/22/08 1.) Calculate the number of vacancies per cubic meter in Au at 900 o C. The energy for vacancy formation is 0.98 eV per atom. Furthermore, the density and atomic weight of Au are 19.32g cm -3 and 196.9 g mol -1 respectively. Determination of the number of vacancies per cubic meter in gold at 900 ° C (1173 K) requires the utilization of Equations (4.1) and (4.2) as follows: N V = N exp - Q V kT = N A ρ Au A Au exp - Q V kT = 6.023 x 10 23 atoms/mol ( 29 19.32 g/ cm 3 ( 29 196.9 g/mol exp - 0.98 eV/ atom 8.62 x 10 - 5 eV/atom - K ( 29 (1173 K) = 3.65 x 10 18 cm -3 = 3.65 x 10 24 m -3 2.) FCC aluminum has a measured density of 2.695Mg m -3 . The lattice parameter of FCC aluminum is 0.404958nm. Calculate the percentage of vacancies in pure Al given that the atomic mass of Al is 26.982g mol -1 . ρ

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## Homework 4 - solutions - MAT 33 Fall 2008 Due: 09/22/08...

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