Posted by Tiffany on .
CS2(g) + O2(g) CO2(g) + SO2(g)
(a) Consider the unbalanced equation above. What is the maximum mass of SO2 that can be produced when 46.0 g of CS2 and 29.0 g O2 react?
(b) Assume the reaction in part (a) goes to completion. Calculate the mass of excess reactant.
I figured out part a and got an answer of 38.7 but I'm not sure how to do the 2nd part. Please help!

Chemistry 
DrBob222,
If you did part a correctly, then you know which is the limiting reagent. To do part b, use the limiting reagent and the same kind of stoichiometry you used for part a to determine moles of the other reagent used, then subtract from the initial amount to determine the amount remaining unreacted. Your answer of 38.7 doesn't help me any. It doesn't have any units (I assume grams) and it doesn't say 38.7 grams of WHAT.

Chemistry 
Tiffany,
It's 37.9 grams of SO2