Question

4. The interionic distance in
NaCl crystal is 0.28 nm, what is
its lattice parameter in
nanometres?​

Answer 1

$\bold{QUESTION\;}$

The interionic distance in

NaCl crystal is 0.28 nm, what is

its lattice parameter in

nanometres?​

$\huge \text{ANSWER}$

In the fcc unit cell of NaCl, along a given edge, chloride ions present at corner sodium ion present at edge centre touch each other.

$\boxed{\;STATEMENT}$

Hence,  the edge length a=2r$_{Na}$ +2r $_{-Cl}$=2(r$+_{Na}$+r$-_{Cl}$)

Here,  (r  +Na  +r  Cl −  ) is the distance between sodium and chloride ions.​   ​  

The length of the edge of the unit cell is twice the distance between sodium and chloride ions in sodium chloride crystal. It is 2X.

 

Answer 2

0.56

Explanation:

r=a/2

a=2r

a=2×0.28=0.56