Calculate the volume of oxygen that was consumed as a result of the combustion of iron powder weighing 3.36 g.

Given:
m (Fe) = 3.36 (g);
V (O2) -?
Decision:
The main formulas that will be used to solve the problem:
n = m in-va / M in – va;
V = n * VM.
Let us write the equation for the reaction of combustion of iron powder:
3Fe + 2O2 = Fe3O4.
n (Fe) = m (Fe) / M (Fe) = 3.36 / 56 = 0.06 (mol).
Given the ratio of the amount of substances in the equation, we get:
3 mol Fe – 2 mol O2
0.06 mol Fe – x mol O2.
x = 0.06 * 2/3 = 0.12 / 3 = 0.04 (mol).
Let’s find the volume of oxygen under normal conditions:
V (O2) = n (O2) * VM = 0.04 * 22.4 = 0.896 (L).
Answer: the volume of oxygen is 0.896 liters.