Calculate the value of Avogadro's number from the following data:
Density of `NaCl = 2.165 g cm^(-3)`
Distance between `Na^(o+)` and `Cl^(Θ)` in `NaCl = 281` pm

Explanation

A unit cell of `NaCl` contains four `NaCl` units.
`:. Z_(eff) = 4, Mw = 23 + 35.5 = 58.5`,
`rho = 2.165 g cm^(-3)` (given)
As distance `Na^(o+)` and `Cl^(Θ)` in `NaCl = 281` pm
`:.` Edge of the unit cell `= 2 xx 281 = 562` pm
Substanding these value in the expression
`rho = (Z_(eff) xx Mw)/(a^(3) xx N_(A) xx 10^(-30))`
`2.165 = (4 xx 58.5)/(((562)^(3)) xx N_(A) xx 10^(-30))`
`N_(A) = 6.09 xx 10^(23)`