Formula mass of `NaCl` is `58.45g mol^(-1)` and density of its pure form is `2.167g cm^(-3)`. The average distance between adjacent sodium and chloride ions in the crystal is `2.814xx10^(-8)cm`. Calculate Avogadro constant.

Answer

`6.05xx10^(23)mol^(-1)`

Explanation

Avogadro's constant `(N_(0))=(ZxxM)/(a^(3)xxrhoxx10^(30))`
Edge length of NaCl (a) = `2(r_(Na^(+))+r_(Cl^(-)))=2xx(2.814xx10^(-8)xx10^(10)"pm")="562.8"`
No. of atoms per unit cell (Z) = 4
Density of NaCl `(rho)=2.167" g cm"^(-3)`
Gram molecular mass of NaCl (M) = `"58.45 g mol"^(-1)`
`N_(0)=(4xx(58.45"g mol"^(-1)))/((562.8)^(3)xx(2xx"167 g cm"^(-3))xx(10^(-30)cm^(3)))=6.05xx10^(23)"mol"^(-1).`