Respuesta :
Answer:
8 Silicon atom are present in unit cell.
16 oxygen atoms are present unit cell.
Explanation:
Number of atoms in unit cell = Z =?
Density of silica = tex]2.32 g/cm^3[/tex]
Edge length of cubic unit cell = a = 0.700 nm = [tex]0.700\times 10^{-7} cm[/tex]
[tex]1 nm=10^{-7} cm[/tex]
Molar mass of Silica = [tex]28.09 g/mol+16.00\times 2=60.09 g/mol[/tex]
Formula used :
[tex]\rho=\frac{Z\times M}{N_{A}\times a^{3}}[/tex]
where,
[tex]\rho[/tex] = density
Z = number of atom in unit cell
M = atomic mass
[tex](N_{A})[/tex] = Avogadro's number
a = edge length of unit cell
On substituting all the given values , we will get the value of 'a'.
[tex]2.32 g/cm3=\frac{Z\times 60.09 g/mol}{6.022\times 10^{23} mol^{-1}\times (0.700\times 10^{-7}cm)^{3}}[/tex]
[tex]Z = 8[/tex]
1 silicon is 2 oxygen atoms. then 8 silicon atoms will be 16 oxygen atoms.
