Question

Phosphorus (P₄) burns in air to give diphosphorus pentoxide. Write a balanced chemical equation for the reaction. Do not have to include states. Include reaction arrow.

Answer 1

P₄ (s) + 5O₂(g)

Answer 2

_P + _O2 -> _P2O5
P-1 P-2
O-2 O-5

In order to balance this equation, you need to first make the reactant oxygen equal the product oxygen. In order to do that, you must make them equal 10.

_P + 5O2 -> 2P2O5


P-1 P-4
O-10 O-10

Now, you need to make the P's equal. This time, you make the coefficient of the reactant phosphorus 4 in order to make it equal the the product phosphorus.

The answer is:

4P+5O2 -> 2P2O5