Question

Agcl has the same structure as that of nacl that length of unit cell of agcl is found to be 555, and the density of agcl is 5.561 gram per centimetre cube find the percentage of sites at and unoccupied

Answer 1

density of a crystal is mass/volumehere mass increases due to filling of impurity thus density increasespercentage of site that are unoccupiedno of agcl atom in unit cell=4density=5.561g/cm^3volume of unit cell=17*10^-23percentage unoccupied=100-percentage occupied=100-{(4*143.5/Na)/5.561}/17*10^-23= 0.24%

Answer 2

Explanation:

Chloride ions form fcc arrangement and silver ions occupy octahedral holes. The number of AgCl molecules (Z) in the unit cell is 4. The molar mass of AgCl is 143.32 g/mol

d=

N

0

×a

3

Z×M

d=

6.023×10

23

×(555×10

−10

)

3

4×143.32

d=5.5677g/cm

3

But the observed density is 5.561g/cm

3

The percentage of sites that are unoccupied =2×

5.5677

5.5677−5.561

×100=0.24%