Sodium crystallises in body centred cubic unit cell. What is the approximate number of unit cells in 4.6 g of sodium ? Given that the atomic mass of sodium is 23 g `mol^(-1)`.

Answer

`6.0xx10^(22)`

Explanation

No. of sodium atom per unit cell of b.c.c. cube `=1//8xx8+1=2`
No. of sodium atoms in 4.6 g of sodium =`((4.6g))/(23gmol^(-1))xx(6.022xx10^(23)mol^(-1))=1.2xx10^(23)`
No. of unit cells in 4.6 of sodium `=(1.2)/(2)xx10^(23)=6.0xx10^(22)`