Calculate what mass of oxide was formed if 5.6 liters of oxygen participated in the combustion reaction of phosphorus.

1. Let’s write the equation of the chemical reaction:

4P + 5O2 = 2P2O5.

2. Find the chemical amount of reacted oxygen (Vm – molar volume, constant equal to 22.4 l / mol):

n (O2) = V (O2) / Vm = 5.6 L / 22.4 L / mol = 0.25 mol.

3. According to the reaction equation, we find the chemical amount of phosphorus oxide, and then its mass:

n (P2O5) = n (O2) / 5 * 2 = 0.25 mol / 5 * 2 = 0.1 mol.

m (P2O5) = n (P2O5) * M (P2O5) = 0.1 mol * 142 g / mol = 14.2 g.

Answer: m (P2O5) = 14.2 g.