Question

Calculate the theoretical density of silver given that it is FCC, has a lattice parameter of 4.0862 Å with an atomic weight of 107.868 g/mole. Compare your value to the density derived experimentally for silver. Why is there a difference? Explain.

Answer 1

Silver lattice is of FCC structure Fcc Face contered Cusic. No of atoons - Fee has 6 faces, - each face have one atom, Contibulation of face alm in cubet. 30 n= kx 6 = 3 6 → 8-cornee Contribution of Corner atom =%8 me YX8 - 1 so total no. of alom in FCC= 1+3= 4 atom - mass nx Mw f-density = volume. = Volume)Y NA n = No. of atoms in FCC = 4 Mw = atanic weight of silver = 107.868 glonol. volume = v= cause volumec a a lattice parametee = 4.0 862 Å= 4:0862X To cm- NA= Aragodalo Number = 6.023x 1023. nxMW 4 x 107.868 / mot 8= 3 X NA= (4.08627768 m) 3 x 6.623 x 18 atom I= 10.50 9/m3 - But silver is rarely found in the pure from, it's density can vary from (10 -12) g/m3 depending upon the type of impurity. so this variation is due to lattice impucity.