What mass of excess reactant remains at the end of the reaction if 90.0 g of so2 are mixed with 100.0 g of o2? 2so2 + o2 → 2so3?

For the reaction 2SO2 + O2 -> 2 SO3, we first determine which is the excess reactant between SO2 and O2. We list down the molar mass of the reactants:

Molar mass of SO2 = 64.0638 g/mol

Molar mass of O2 = 32 g/mol

Using the stoichiometry of the reaction, we then calculate the amount of oxygen that will react with 90.0 g of SO2.

90.0 g SO2 x 1 mol SO2/64.0638 g x 1 mol O2/ 2 mol SO2 x 32 g O2/mol = 22.4776 g O2

Thus, we can conclude that O2 is the excess reactant while SO2 is the limiting reactant. Subtracting 22.4776 g O2 from the initial 100.0 g O2, we get 77.5224 g O2 left after the complete reaction of 90.0 g SO2. 

10 years is the answer