Write the reaction equation for the formation of iron oxide Fe3O4 from simple substances.

Write the reaction equation for the formation of iron oxide Fe3O4 from simple substances. Determine the mass of the oxide if 112 liters of oxygen were spent on its formation

Given:
V (O2) = 112 l
To find:
m (Fe3O4) =?
Decision:
1) Let’s compose the equation of the chemical reaction, we know the number of liters of oxygen, and let the mass of Fe3O4 be x g.
3Fe + 2O2 = Fe3O4
2) Find the molecular weight of Fe3O4 = 56 x 3 + 16 x 4 = 232 g / mol.
3) Vm (O2) = 22.4 x 2 = 44.8 L / mol.
4) 112 L: 44.8 L / mol = xg: 232 g / mol.
x = (112 x 232): 44.8 = 580 g.
Answer: m (Fe3O4) = 580 g.