Solid carbon dioxide is called “Dry Ice”. The “Dry Ice” is molecular crystal and the unit cell there — Inorganic Chemistry — Solid State Chemistry Question
Carbon dioxide II
Solid carbon dioxide is called “Dry Ice”. The “Dry Ice” is molecular crystal and the unit cell thereof is a face center cubic structure consisting of carbon dioxide molecules.
11.1.
Calculate the density of “Dry Ice”, ρ, when the edge length of the cubic unit cell of “Dry Ice” is 0.56 nm.
Model Answer
CO2 (M = 44.0 g mol-1): face-centered cubic lattice, 4 molecules per one unit lattice:
ρ = (44.0 × 4) / ((0.56 × 10^-9 m)^3 × 6.02 × 10^23 mol^-1) = 1.67 × 10^6 g m^-3
11.2.
Calculate the number of carbon dioxide molecules, N, in the cuboid “Dry Ice” of 20 cm × 10 cm × 5.0 cm.
Model Answer
N = (0.20 × 0.10 × 0.050) × 1.67 × 10^6 × 6.02 × 10^23 / 44.0 = 2.28 × 10^25
N = 2.3×10^25 molecules
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