Question 1: A metal is found to have BCC structure, a lattice constant of 3.31 A

Question

Question 1: A metal is found to have BCC structure, a lattice constant of 3.31 A and a density of 16.6 g/cm3. Determine the atomic weight of this element. What is this element? Question 2: The atomic weight, density, and atomic radius for three hypothetical alloys are listed in the following table. For each, determine whether its crystal structure is FCC, BCC, or simple cubic and then justify your determination. Alloy Atomic Weight (g/mol) 43.1 184.4 91.6 Density (g/cm") 6.40 12.30 9.60 Atomic Radius (nm) 0.122 0.146 0.137 Question 3: Iron (Fe) undergoes an allotropic transformation at 912 °C, upon heating from a BCC (a- phase) to an FCC (y-phase). Assume Fe has an atomic radius of 0.124 nm in both cases, and an atomic weight of 55.85 g/mol. i) Calculate the theoretical density for both structures and discuss the difference. ii) Explain how the density of BCC iron relates to what you find on the internet for pure iron? [GI* Question 4: What is the largest atom that can fit in the tetrahedral and octahedral interstitial region of FCC in terms of r?

Explanation / Answer

3.31 angstroms = 3.31x10-8 cm

Volume = l3 = (3.31x10-8 cm)3 = 3.626 x 10-23 cm3/ unit cell

Unit cells = 2.758 x 1022 unit cells/cm3

2.758 x 1022 unit cells/cm3 * 2 atoms/unit cell = 5.516 x 1022 atoms/cm3

5.516 x 1022 atoms/cm3 * (1 mol / 6.022 x 1023 atoms) = 0.0916 mol/cm3

0.0916 mol/cm3 = density/atomic weight

0.0916 mol/cm3 = 16.6 g/cm3 /atomic weight

atomic weight = 181.22 g/mol

Element is Tantalum

As per chegg norms only 1 question per post to be answered. Please post the other as a seperate question

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.