Question

When gold crystallizes it forms fcc. The unit cell edge length is 408pm. Calculate the density of gold. Molar mass of gold is 197g/mol

Answer 1

Answer:

Explanation:

Atomic mass of gold is 197 g/mol. 1 mole of gold weighs 197 g.  1 mole of gold contains 6.023×1023 atoms. Hence, 6.023×1023 atoms of gold weighs 197 g. 1 atom of gold weighs 6.023×1023 atoms197 g​

A fcc unit cell of gold contains 4 atoms.

The mass of the unit cell of gold = mass of 4 atoms of gold

=6.023×1023 atoms197 g​×4 atoms=1.3×10−21 g.

Convert the unit from g to Kg.

The mass of the unit cell of gold =1.3×10−21 g×1000 g1 kg​=1.3×10−24 Kg.

Answer 2

Answer:

Atomic mass of gold is 197 g/mol. 1 mole of gold weighs 197 g. 1 mole of gold contains 6.023×10

23

atoms. Hence, 6.023×10

23

atoms of gold weighs 197 g. 1 atom of gold weighs

6.023×10

23

atoms

197 g

A fcc unit cell of gold contains 4 atoms.

The mass of the unit cell of gold = mass of 4 atoms of gold

=

6.023×10

23

atoms

197 g

×4 atoms=1.3×10

−21

g.

Convert the unit from g to Kg.

The mass of the unit cell of gold =1.3×10

−21

g×

1000 g

1 kg

=1.3×10

−24

Kg.