Question

1)Calculate the number of molecules of the compound and the number of atoms of each of the elements in 3.98 moles of SO3 . ? molecules, ? atoms of S, ? atoms of O 2) Calculate the number of molecules of the compound and the number of atoms of each of the elements in 3.35 moles of P4O12. ? molecules, ?atoms of P, ? atoms of O

Answer 1

We are given moles of SO3

Number of molecules = moles x Avogadro number

Therefore

3.98*6.02 E23=2.39 E24 SO3 molecules

1 molecule of SO3 has 1 atom of S

Therefore number of atoms of S in 2.39E24 SO3 molecules contains

2.39 E24 SO3 molecule x 1 S atom / 1 SO3 molecule

=2.39 E24 S atom

1 molecule of SO3 has 3 atoms of O so

Number of atoms of O

2.39 E24*3/1=7.17 E24 O atoms.

2)

Number of molecules of P4O12

3.35*6.02E23=2.02 E24 P4O12 molecules

1 molecule of P4O12 has 4 atoms of P

Number of atoms of P

2.02E24*4/1=8.08 E24 P atoms

Number of O atom

2.02E24*12/1=2.42 E25 O atoms