Question

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

Answer 1

`"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:

`CH_4(g) +2O_2(g) rarr CO_2(g) + 2H_2O(g) + Delta`

Where `Delta="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 `"endothermic reaction"`.

`CaCO_3(s) + Delta rarr CaO(s) + CO_2(g)`

`CO_2(g) + Delta rarr C(s) + O_2(g)`