Question

Calculate the number of moles present in 72 g oxygen molecules

Answer 1

Explanation:

a) 12 g of carbon

Given mass : 12 g

No. of moles =

mole. mass

Given mass

=

12

12

=1 mole

No. of molecules = No. of moles × Avagadro No.

=1×6.22×10

23

=6.022×10

23

molecules

b) 64 g of oxygen

Given mass: 64 g

No. of moles =

mole. mass

Given mass

=

16

64

=4 mole

No. of molecules = No. of moles ×N

A

=4×6.22×10

23

=24.088×10

23

molecules

c) 72 g of water

Given mass =72 g

Molecular mass =18 g

No. of moles =

18

72

=4 mole

No. of molecules =4×6.22×10

23

=24.088×10

23

molecules