Question

$r_{N{a}^{+}}$ and $r_{C{l}^{-}}$ represents radius of $N{a}^{+}$ and $C{l}^{-}$ ions respectively. If ${}^{\prime }{n}^{\prime }$ is the number of $NaCl$ units per unit cell then give equation you will use to obtain molar volume.

Answer 1

Edge length of unit cell ${}^{\prime }{a}^{\prime }=2(r_{N{a}^{+}}+r_{C{l}^{-}})$
Volume of unit cell $=a^3=8(r_{N{a}^{+}}+r_{C{l}^{-}}{)}^3$
Volume occupied by one mole of $NaCl$
$=\frac{8(r_{N{a}^{+}}+r_{C{l}^{-}}{)}^3}{n}\times N_A$
where $N_A=6.023\times {10}^{23}$.