There is a problem that I am completely stuck on and it deals with thermochemistry, specifically on calculating the amount of heat released in a reaction. The question is, "how much carbon dioxide must be produced to release 1200.0 J of energy?" using the balanced equation below:

C3H8 + 5 O2 → 3 CO2 + 4 H2O, ΔH=-2044kJ.

2044kJ produced three moles. how much is released on 1.2kj?

1.2kj/2044 * 3 is the number of moles of CO2 released.