# If the heat of reaction is written on the reactant side of a chemical equation, what does that indicate about the reaction?

##### 1 Answer
May 28, 2018

It means that the reaction is $\text{ENDOTHERMIC....}$

#### Explanation:

Combustion reactions are of course $\text{EXOTHERMIC....}$...and we could represent such a reaction as....

$C {H}_{4} \left(g\right) + {O}_{2} \left(g\right) \rightarrow C {O}_{2} \left(g\right) + 2 {H}_{2} O \left(l\right) + \Delta$

Such a reaction possibly cooked your dinner. And certainly we could treat the energy OUTPUT quantitatively according to the reaction stoichiometry.

On the other hand, we could treat an endothermic reaction similary...and here we represent the BOILING of water, a physical reaction...

${H}_{2} O \left(l\right) + \Delta \rightarrow {H}_{2} O \left(g\right)$...

And again this process could be addressed quantitatively. Capisce?