Answer: 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:
[tex]\rho=\frac{Z\times M}{N_{A}\times a^{3}}[/tex]
where,
[tex]\rho[/tex] = density of CaO = [tex]3.34g/cm^3[/tex]
Z = number of atom in unit cell = ?
M = atomic mass of CaO = 56 g/mol
[tex]N_{A}[/tex] = Avogadro's number = [tex]6.022\times 10^{23}[/tex]
a = edge length of unit cell = [tex]481pm=481\times 10^{-10}cm[/tex] (Conversion factor: [tex]1cm=10^{10}pm[/tex] )
Putting values in above equation, we get:
[tex]3.34=\frac{Z\times 56}{6.022\times 10^{23}\times (481\times 10^{-10})^3}\\\\Z=3.997\approx 4[/tex]
Hence, the number of formula units of CaO in one unit cell are 4
