Question

If 3.8 moles of P4 are used, how many moles of O2 are needed?

Answer 1

1) Write the chemical equation.

`P_4+O_2\rightarrow P_4O_(10)`

2) List the elements in the reactants and in the products.

Reactants.

P: 4

O: 2

Products

P: 4

O: 10

Balance O.

`P_4+5O_2\rightarrow P_4O_(10)`

3) Moles of O2 needed.

The molar ratio between P4 and O2 is 1 mol P4: 5 mol O2.

`mol\text{ }O_2=3.8\text{ }mol\text{ }P4*\frac{5\text{ }mol\text{ }O_2}{1\text{ }mol\text{ }P_4}=19\text{ }mol\text{ }O_2`

If 3.8 mol P4 are used, 19 mol O2 are needed.

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