Question

How many molecules of SO₃ can be formed from 0.94 moles of O₂ (assuming excess SO₂) from the following UNBALANCED equation?SO₂(g) + O₂(g) → SO₃(g)

Answer 1

1) Balance the chemical equation.

`SO_(2(g))+O_(2(g))\rightarrow SO_(3(g))`

List the elements in the reactants.

S: 1

O: 4

List the elements in the products.

S: 1

O: 3

S is already balanced.

Balance O

`2SO_2+O_2\rightarrow2SO_3`

List the elements in the reactants.

S: 2

O: 6

List the elements in the products.

S: 2

O: 6

The balanced equation is

2) Moles of SO3 formed from O2.

The molar ratio between SO3 and O2 is 2 mol SO3: 1 mol O2.

`mol\text{ }SO_3=0.94\text{ }mol\text{ }O_2*\frac{2\text{ }mol\text{ }SO_3}{1\text{ }mol\text{ }O_2}=`
`mol\text{ }SO_3=1.88\text{ }mol\text{ }SO_3`

3) Convert moles of SO3 to molecules of SO3.

Avogadro's number is 6.022*10^23

1 mol SO3= 6.022*0^23 molecules of SO3.

`molecules\text{ }SO_3=1.88\text{ }mol\text{ }SO_3*\frac{6.022*10^(23)\text{ }molecules\text{ }SO_3}{1\text{ }mol\text{ }SO_3}`
`molecules\text{ }SO_3=1.132136*10^(24)\text{ }molecules\text{ }SO_3`

1.13*10^24 molecules are formed from 0.35 mol O2.

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