# In an exothermic reaction, is heat a product?

Feb 27, 2017

It can be considered to be a product.......

#### Explanation:

Burn a hydrocarbon in air, and heat is a result of the reaction......

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

Normally we would report the enthalpy change as $\Delta {H}_{\text{rxn}} = - 891 \cdot k J \cdot m o {l}^{-} 1$. The negative sign indicates that the reaction is exothermic; i.e. heat is a result of the reaction.

We could equally represent the reaction as:

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

Where $\Delta$ represents the heat output.

Feb 27, 2017

Heat is evolved in an exothermic reaction, but conventionally you would not regard heat as a "product"......

#### Explanation:

The term "product" would normally be used to describe a substance that is produced as a the result of a chemical reaction. However, heat is not a substance, it is a term used to denote the flow of energy (in this case from the reaction medium to the external environment).

So heat is evolved in an exothermic reaction, but it is not a "product".