Classify each chemical reaction as endothermic or exothermic.

Question

Classify the following:

2CO2(g)+heat —> 2CO(g)+O2(g)

2H2(g)+O2(g) —> 2H2O(I)+heat

N2(g)+2O2(g)+heat —> 2NO2(g)

2C2H2(g)+5O2(g) —> 4CO2(g)+2H2O(I)+heat

Answer 1

If heat is being added to the system, it is endothermic

If heat is being released by the system to the surroundings, it is exothermic

So, simply look to see if heat is a reactant (on the left side), or if it is a product (on the right side)

If on the left (a reactant), it is being added and it is ENDOTHERMIC

If on the right (a product), it is being released and it is EXOTHERMIC