Plz expalin this question again i m not getting the concept of spacing... 6.04 x 103 ex. 10. the density f a particular crystal of li

Some questions just want to understand your depth of knowledge about it..rather than being formula based..we use formula for atoms, not molecules... please note it down! That density formula is not applicable for molecules, Shweta!

In this question, you have to devise to your practical knowledge of finding the edge length...'cc' was the catching point.

really sir for molecules we can't use density formuka

why

Because, if you look at the density formula, it has 'M' in it, which is atomic mass..you tell me, in molecules like LiF or CaF2 what will you take 'M'? it's not possible.

sir we take its molar mass for lif it's 25.6 grampermole

I send u a picture there they have used

this sir

Dear Shweta, here it is mentioned that CsCl has cubic structure..and we already know that CsCl has BCC type structure, where Cs is assumed to be at centre and Cl is at the corners...so, the overall contribution of Cs is 1 and Cl is 1 in a cubic crystal...that's why they have taken simply the molecular mass.

ok sir but sir here can't we use density direct formula

i am confused in spacing and edge length here spacing is given plz give explanation for thos

got shweta here lif is placed on the edge length at a gap of 2.01 A ...

so you can find the no of ions on edge length = edge length/spacing