Carbon monoxide is completely burned, at a pressure of 1 bar, in excess air. The reactants come in at 100 C and the products leave at 1000 C. Heat loss is negligible.
What is the percent excess air?

Since this is homework, what do you think the answer is, and how did you arrive at that answer.

I know how to solve excess air problems given compositions of the in and out streams, but how do I do this?

Can you help me out?