Engineering Board Exam Reviewer · Engineering Materials · hard

α-Iron is BCC with an atomic radius of 0.1241 nm and an atomic weight of 55.85 g/mol. What is its theoretical density?

  1. 15.76 g/cm3
  2. 7.88 g/cm3
  3. 8.58 g/cm3
  4. 3.94 g/cm3

Answer

B. 7.88 g/cm3

Solution

a = 4R/sqrt(3) = 0.2866 nm. = 2(55.85)/[(0.2866 × 10-7)3(6.022 × 1023)] = 7.88 g/cm3.

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