# Chemistry percent yield problem involving STP?

Consider the reaction: 2 SO2(g) + O2(g) -> 2 SO3(s) A.) If 285.5 mL of SO2 is allowed to react with 158.9 ml of O2 (both measured at STP), what is the limiting reactant and the theoretical yield of SO3? I got the correct answers given from the book for this part, which are that SO2 is the limiting reactant... show more Consider the reaction:

2 SO2(g) + O2(g) -> 2 SO3(s)

A.) If 285.5 mL of SO2 is allowed to react with 158.9 ml of O2 (both measured at STP), what is the limiting reactant and the theoretical yield of SO3?

I got the correct answers given from the book for this part, which are that SO2 is the limiting reactant and the theoretical yield is 0.0127 mol of SO3.

B.) If 2.805 g of SO3 is collected (measured at STP), what is the percent yield for the reaction?

I need some help with this part. The answer given in 65.6 percent. I know how to calculate percent yield, but I don't know how to get that answer for this question. Could someone answer and explain please?

Thanks