copper crystallises in face centred cubic lattice.calculate the number of unit cells in 1.2 gm of copper.
Answers
Given : Given Mass of Copper = 1.2 gm
Copper crystallises in fcc
To find :- Number of unit cells =?
Solution:
- FCC stands for face centered cubic structure
- In FCC atoms are located in the centre of cubic face contain six atoms and the corners that contain eight atoms.
- Eight unit cell share corner among themselves because each of the corner is the corner of another cube.
- It is given that copper crystallises in fcc cubic lattice .
- As we know that fcc contain 4 atoms/ unit cell.
- Given mass of copper
= 1.2 g
- The molecular mass of copper (Cu) is
= 63.5 g
- 63.5 g of copper contains
= 6.022 × 10^23
then 1.2 g if copper will contain
= 1.2 × 6.022 × 10^23/ 63.5
= 11.38 × 10^21 atoms
- If 4 Cu atoms contain
= 1 unit cell
then, 11.38 × 10^21 atoms of Cu will contain
= 11.38 × 10^21 × 1/4
= 2.845 × 10^21 unit cells.
- So, The no. of unit cells that copper atom contain is 2.845 × 10^21 unit cells.