Find the mass of oxygen that reacted with zinc, if this resulted in 8.1 g of zinc oxide?

1. Zinc reacts with oxygen according to the equation:
2Zn + O2 = 2ZnO;
2.Calculate the chemical amount of zinc oxide:
n (ZnO) = m (ZnO): M (ZnO);
M (ZnO) = 65 + 16 = 81 g / mol;
n (ZnO) = 8.1: 81 = 0.1 mol;
3. Determine the amount of reacted oxygen:
n (O2) = n (ZnO): 2 = 0.1: 2 = 0.05 mol;
4. find the mass of oxygen:
m (O2) = n (O2) * M (O2) = 0.05 * 32 = 1.6 g.
Answer: 1.6 g.