# What type of reactions require energy in order to take place?

Oct 18, 2016

$\text{Endothermic reactions..........}$

#### Explanation:

When a fuel is combusted with dioxygen, typically an EXOTHERMIC reactions occurs, with the release of energy, and the energy can be used to do useful work:

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

Where $\Delta = \text{Energy}$.

This energy can be quantified on the basis of the amount of fuel used.

On the other hand, a reaction that requires energy, i.e. where energy is treated as a reactant is classified as an $\text{endothermic reaction}$.

$C a C {O}_{3} \left(s\right) + \Delta \rightarrow C a O \left(s\right) + C {O}_{2} \left(g\right)$

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