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

Calculate the value of Avogadro's number from the following data: Dens

1.	Calculate the value of Avogadro's number from the following data: Density of NaCl=2.165 g cm^(-3). Distance between Na^+ and Cl^- in NaCl=281 pm
Answer» Solution :A unit cell of NaCl CONTAINS 4 NaCl units, THEREFORE , Z=4 , M=23+35.5=`58.5 g MOL^(-1), RHO =2.165 g cm^(-3)` As distance between `Na^+` and `Cl^-` =281 pm `therefore` Edge of the unit cell =`2xx281`=562 pm (Edge is the distance from `Na^+` to `Na^+` ion or `Cl^-` to `Cl^-` ion. Substituting these values in the expression , `rho=(ZxxM)/(a^3xxN_0)` `2.165 g cm^(-3)=(4xx58.5 g mol^(-1))/((562xx10^(-10) cm)^3 xxN_0)` or `N_0=6.09xx10^23 mol^(-1)`