Question

Number of H and O atoms in 100grams of h20

Answer 1

# O atoms =
`3.3407325*10^(24)`

# H atoms =
`2(3.3407325*10^(24)) = 6.681465*10^(24)`

Step-by-step explanation:

Stoichiometry

We're given:

• 100 g of H2O
• # H atoms?
• # O atoms?

1) Find the moles of H2O.

`n=(m)/(M)` where n is moles, m is mass and M is molar mass

`n=(100)/(2(1.01)+16.00)`

`n=(100)/(18.02)`

`n=5.54938956715\hspace{4}mol`

2) Find the number of molecules of H2O.

n × Avogadro's number = # atoms

`5.54938956715*6.02*10^(23)\\=3.3407325*10^(24)`

∴ There are
`3.3407325*10^(24)` molecules of H2O.

3) Find the number of atoms of H and O.

There are 2 H atoms and 1 O atom in every molecule of H2O.

Therefore...

# O atoms =
`3.3407325*10^(24)`

# H atoms =
`2(3.3407325*10^(24)) = 6.681465*10^(24)`