Chromium (atomic mass 52.00 g/mol)crystallizes in a body-centered cubic unit cell.If the length of an edge of the unit cell is 289 pm,what is the density (in g/cm³)of chromium? A) 3.58 g/cm³ B) 7.15 g/cm³ C) 13.7 g/cm³ D) 14.3 g/cm³ E) 21.3 g/cm³

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Quizplus · Accepted Answer

In a body-centered cubic (bcc) unit cell, there are 2 atoms per unit cell. The density can be calculated using the formula: density = (mass of atoms in the cell / volume of the cell). The mass of the atoms in the cell is (2 atoms * 52.00 g/mol) / Avogadro's number (6.022 x 10^23 atoms/mol). The volume of the cell is (289 pm)^3, but first, convert pm to cm (1 pm = 1 x 10^-12 m = 1 x 10^-10 cm), so the volume in cm^3 is (289 x 10^-10 cm)^3. Plugging these values into the density formula and converting to the appropriate units gives a density of approximately 7.15 g/cm^3.

Chromium (Atomic Mass 52