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A metal crystallizes in a body-centered cubic unit cell. The radius of one atom = 2.30 x 10 -8 cm. The density of the metal is 0.867 g/cm^3 . What is molar mass of metal?

Respuesta :

Answer:

25.41 g/mol is molar mass of metal.

Explanation:

Number of atom in BCC unit cell = Z = 2

Density of metal = [tex]0.867 g/cm^3[/tex]

Edge length of cubic unit cell= a = ?

Radius  of the atom of metal = r = [tex]2.30\times 10^{-8} cm[/tex]

[tex]a=2\times r=2\times 2.30\times 10^{-8} cm=4.60\times 10^{-8} cm[/tex]

Atomic mass of metal =M

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]0.867 g/cm^3=\frac{2\times M}{6.022\times 10^{23} mol^{-1}\times (4.60\times 10^{-8} cm)^{3}}[/tex]

[tex]M = 25.41 g/mol[/tex]

25.41 g/mol is molar mass of metal.