KBr has fcc str.The density of KBr is 2.75 g/cm cube.Find the distance b/w K+ and Br- .

For PbS

M= 239g

Z= 4.

Let distance between ions = (R++R-)

d= 2.75g/cm

NA=6.023x1023.

Br- is present at corners while K+ is present at edge centers.

so

 

(2R++2R-)=a

or

2(R++R-)=a.................(1)

 

we know that...

Form e.q.(1)

on Substituting the values and calculating you will get the value of  (R++R-).

Good luck.

  • -5

In KBr, the anions actually form the face centred cubic structure and all the octahedral voids are occupied by the cations.

Therefore the distance between cation and anion will be just half the unit cell parameter.

The unit cell parameter can be calculated from the known formula

d=ZM/a3Na

  • 0

 In KBr, the anions actually form the face centred cubic structure and all the octahedral voids are occupied by the cations.

 

Therefore the distance between cation and anion will be just half the unit cell parameter.

 

The unit cell parameter can be calculated from the known formula

 

d=ZM/a3Na

  • -2

In KBr, the anions actually form the face centred cubic structure and all the octahedral voids are occupied by the cations.

Therefore the distance between cation and anion will be just half the unit cell parameter.

The unit cell parameter can be calculated from the known formula

d=ZM/a3Na

  • 1
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