Question

How many atoms are there in 35.7 mole sample of silicon?

Answer 1

Answer:

=

7.505

×

10

22

atoms. (rounded to third place of decimal)

Explanation:

Average atomic weight of Silicon, Si atom is

28.0855

units.

We know from Mole concept that

1

mole is

6.022

×

10

23

of anything. This number is called Avogadro's number.

Also that

1

mole of Silicon weighs

28.0855

g.

Therefore,

28.0855

g of Silicon contains

6.022

×

10

23

of Silicon atoms.

3.5

g of Silicon contains number of atoms

=

6.022

×

10

23

28.0855

×

3.5

=

7.505

×

10

22

atoms. (rounded to third place of decimal)