1. Tardigrade
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  3. Chemistry
  4. Iron oxide FeO, crystallises in a cubic lattice with a unit cell edge length of 5.0 mathringA. If density of the FeO in the crystal is 4.0 g cm -3, then the number of FeO units present per unit cell is . (Nearest integer) Given: Molar mass of Fe and O is 56 and 16 g mol -1 respectively. N A =6.0 × 1023 mol -1

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Q. Iron oxide $FeO$, crystallises in a cubic lattice with a unit cell edge length of $5.0 \mathring{A}$. If density of the $FeO$ in the crystal is $4.0\, g \,cm ^{-3}$, then the number of $FeO$ units present per unit cell is ______ . (Nearest integer)
Given: Molar mass of $Fe$ and $O$ is $56$ and $16 \, g \, mol ^{-1}$ respectively.
$N _{ A }=6.0 \times 10^{23} mol ^{-1}$

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Solution:

$d =\frac{ Z \times M }{ N _0 \times a ^3} $
$ 4=\frac{ Z \times 72}{6 \times 10^{23} \times 125 \times 10^{-24}}$
$Z=4.166 \simeq 4$