Density of unit cell calculations
Solid State · Chemistry
Study notes
BCC iron: r = 126 pm, M = 55.85. Calculate density. Step 1: BCC: Z = 2; a = 4r/√3 = 4 × 126/1.732 = 291 pm. Step 2: a = 291 × 10⁻¹⁰ cm = 2.91 × 10⁻⁸ cm; a³ = 2.464 × 10⁻²³ cm³. Step 3: ρ = 2 × 55.85/(2.464 × 10⁻²³ × 6.022 × 10²³). Step 4: = 111.7/14.84 = 7.53 g/cm³ (real Fe: 7.87 — close!). Small radius errors cube up — measure r carefully.