Question

The number of unit cells in 58.5g of NaCl is nearly

Answer 1

n(moles)= m(g)÷M
putting values
n=58.5÷58.5
n=1
now we have to calculate the no of unit cell in 1 mol of NaCl
HERE IT IS
since i unit cell of NaCl= 4 NaCl units...
so unit cells =n÷4= avogadros number÷4=____solve it!!!

Answer 2

NaCl ( rock salt ) structure:

no. of edge center atoms = 12(edges) x 1/4 (each edges shared by 4 units)

=3

no. of body centred atoms = 1( center position) x 1 ( single atom present)

= 1

no of corner atoms = 8 (corners) x 1/8 (counribution of each atom to a unit cell )

= 1

no. of face centered atoms = 6 (no. of faces in a cube) x 1/2 (atoms contribution to single unit cell)

=3

there are 8 cubes ( units) in an ideal NaCl structure

coordination ration of NaCl=6:6

rank of NaCl = 4 ( no. of formula units )

no of NaCl molecule in aunit cell is 4

in 58.5 gm of NaCL no of mole is 1

in 1 mole of NaCl no of unit cell is Na/4

6.022 x 10^23/4

=1.5 x 10^23