Given that the density of CaO ( s ) is 3.34 g/cm 3 and that the length of an edge of a unit cell is 481 pm, determine how many formula units of CaO there are in a unit cell.

The number of formula units of CaO in one unit cell are 4

Explanation:

To calculate the number of formula units, we use the equation used to calculate the density of metal, which is:

where,

= density  of CaO =

Z = number of atom in unit cell = ?

M = atomic mass of CaO = 56 g/mol

= Avogadro's number =

a = edge length of unit cell =    (Conversion factor:    )

Putting values in above equation, we get:

Hence, the number of formula units of CaO in one unit cell are 4

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