**molar mass Fe = 55.845 g/mol**

**1 mole = 6.022x10 ^{23} entities**

density of solid Fe = 7.87 g/cm^{3}

**Calculate the atoms present per cubic centimeter of Fe**

$\frac{\mathbf{atoms}}{{\mathbf{cm}}^{\mathbf{3}}}\mathbf{=}\frac{\mathbf{7}\mathbf{.}\mathbf{87}\mathbf{}\overline{)\mathbf{g}\mathbf{}\mathbf{Fe}}}{{\mathbf{cm}}^{\mathbf{3}}}\mathbf{\times}\frac{\mathbf{1}\mathbf{}\overline{)\mathbf{mol}\mathbf{}\mathbf{Fe}}}{\mathbf{55}\mathbf{.}\mathbf{845}\mathbf{}\overline{)\mathbf{g}\mathbf{}\mathbf{Fe}}}\mathbf{\times}\frac{\mathbf{6}\mathbf{.}\mathbf{022}\mathbf{\times}{\mathbf{10}}^{\mathbf{23}}\mathbf{}\mathbf{Fe}\mathbf{}\mathbf{atoms}}{\mathbf{1}\mathbf{}\overline{)\mathbf{mol}\mathbf{}\mathbf{Fe}}}$

**atoms/cm ^{3} = 8.486x10^{22} Fe atoms/cm^{3}**

**Calculate the number of**** unit cells are present per cubic centimeter of Fe**

*recall the # of atoms present **per 1 BCC unit cell*: *corner atoms contribute 1/8 and the center atom contribute 1*

$\mathbf{\#}\mathbf{}\mathbf{of}\mathbf{}\mathbf{atoms}\mathbf{=}\left(\mathbf{8}\mathbf{\times}\frac{\mathbf{1}}{\mathbf{8}}\right)\mathbf{+}\mathbf{1}$

**# of atoms = 2 per 1 unit cell**

The density of solid Fe is 7.87 g/cm^{3}. How many atoms are present per cubic centimeter of Fe? As a solid, Fe adopts a body-centered cubic unit cell. How many unit cells are present per cubic centimeter of Fe? What is the volume of a unit cell of this metal? What is the edge length of a unit cell of Fe?

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