Question

Consider the reaction at equilibrium:
2NO2(g) <---> N2O2(g) + O2(g)
for which, H = −20.4 kJ · mol−1. If you
decrease the temperature of the system, what will occur?

Answer 1

Rewrite the equations so the heat shows.
2NO2(g) <---> N2O2(g) + O2(g) + heat
Now, decreasing T means the reaction will try to heat the reaction. so it shifts to the ......

Answer 2

how do I know which side heat is on?

Answer 3

In this case I wrote it on the correct side which is the right side. In any case however, remember that -delta H means the reaction is exothermic and + delta H means the reaction is endothermic. Look at this reaction; the problem tells you that delta H is -20 kJ/mol which means it is exothermic so you write heat as a product. If delta H is a + number it means the reaction is endothermic so you write heat as a reactant.

Answer 4

does the decrease mean the reaction shifts to the right?