Calculate the volume of oxygen under normal conditions if 4 mol of V2O5 was used in the decomposition reaction.

Given:
n (V2O5) = 4 mol
Vm = 22.4 l / mol

To find:
V (O2) -?

Decision:
1) Write the equation of a chemical reaction:
2V2O5 = (t-700-1250C) => 4VO2 + O2 ↑;
2) Determine the amount of substance O2 (taking into account the coefficients in the reaction equation):
n (O2) = n (V2O5) / 2 = 4/2 = 2 mol;
3) Calculate the volume of O2 (under normal conditions):
V (O2) = n (O2) * Vm = 2 * 22.4 = 44.8 liters.

Answer: The O2 volume is 44.8 liters.